Mike Thorn (UK) If you ask someone to think of Oxford, they will not usually picture warm tropical beaches and azure coral seas. However, go back to the middle Jurassic and you would be hard pushed to find a dreaming spire or student on a bicycle anywhere. At that time, around 160 million years ago, Oxfordshire lay beneath a shallow, tropical seaway at about the same latitude that the southern Mediterranean occupies today. Over the course of the middle Jurassic, this seaway varied in depth, but remained close to nearby land masses from which a lot of sediment was derived (Fig. 1). A great thickness and variety of limestones, sandstones and clays were deposited over several tens of millions of years. Fig. 1. Southern England during the middle Jurassic, 160 million years ago. During the nineteenth and early twentieth centuries, there were many working quarries in the Oxford area, exploiting the abundant clay and limestone for the brick and building stone industries. Quarrymen were frequently paid to look out for fossils and these turned up in abundance, fuelling the academic debates on evolution taking place at the time. Fig. 3. Geological Context for Kirtlington Quarry and Dry Sandford Pit. Sadly, many of these quarries have now been filled in and, for the casual fossil hunter in Oxfordshire, it might seem that there are now few opportunities to collect. However, Kirtlington Quarry and Dry Sandford Pit are two old quarries which are open to the public and at which there is … Read More
Stephen Moreton (UK) Our journey around Ireland concludes in Ulster. This comprises Northern Ireland, which is part of the UK, and the counties of Cavan, Donegal and Monaghan, which are part of the Republic of Ireland. As geology is no respecter of politics, the national border is ignored here. I assure my gentle readers that this is not intended as a political statement! The geology consists of metamorphic rocks and granite intrusions in the west, a huge expanse of Tertiary basalt in the eastern half, and a series of Tertiary granite intrusions in the southeast corner. Carboniferous limestone makes an appearance in some places, but is not as well endowed with minerals as further south. Fig. 1. The four regions of the island of Ireland. Fig. 2. Ulster in more detail. Donegal, occupying the northwest corner of the island, has such a varied geology that it has long been a favourite venue for university ﬁeld trips. In spite of this variety, there are few mining sites. Lead has been mined at Glenaboghil, Keeldrum and Glentogher, but these old mines are not noted for specimens. However, minor yellow powdery greenockite occurs at the ﬁrst location and green coatings of pyromorphite at the second. What it lacks in mines, the county makes up for in silicate minerals. The beryl occurrence at Sheshkinnarone is probably the best known. Finger size green and blue-green prisms in a white quartz matrix occur at several spots here. The richest is just outside the garden wall of … Read More
Stephen Moreton (UK) In the ﬁrst two articles of this series, we looked at Leinster and Munster. Continuing in a clockwise fashion brings us to Connaught. Some of Ireland’s oldest rocks are to be found here, forming the Ox Mountains. The rugged and mountainous west is dominated by metamorphic rocks and a series of granite intrusions. Inland, Carboniferous limestone prevails. Fig. 1. The four regions of the island of Ireland. Fig. 2. Connaught in more detail. Where the latter abuts Devonian sediments is found the jewel in the crown of Irish mineralogy – Tynagh Mine. This giant polymetallic deposit, near Loughrea in County Galway, was discovered in the 1960s and yielded close to a million tonnes of lead, zinc and copper. Much of this was as sulphides dispersed through black mud ﬁlling a huge depression in the limestone. This was formed by acid from rotting pyrite dissolving the country rock. Extensive oxidation and remobilisation of the primary ores produced hundreds of thousands of tonnes of smithsonite, cerussite, malachite and azurite. Scores of rarer species, such as linarite, anglesite, brochantite, native silver and numerous arsenates were also present. Fig. 3. Malachite, from Tynagh, Co. Galway. 64mm x 35mm botryoidal and stalactitic mass dug out of the tips. Sadly, collectors were slow to learn of this treasure and most was sent to the crusher. By the time they did realise something glorious was going on, most was already turned into smelted metal. A fickle attitude on the part of management did not … Read More
Stephen Moreton (UK) In the second part of our tour of Ireland, we head for Munster, which occupies the southwest corner of the island. Geologically, the rocks are mostly inland Carboniferous shales and limestones, with Devonian sandstones forming the coastal peninsulas. All host mineral localities of note. Fig. 1. The four regions of the island of Ireland. Fig. 2. Munster in more detial. Starting in County Waterford, mineral collectors will tend to head for the copper coast – a group of nineteenth century copper mines centred on the coastal village of Bunmahon. The magnificent crystallised native copper and cuprite these mines yielded in the past are elusive nowadays. On the other hand, post-mining oxidation in the dumps and sea cliff levels and outcrops has produced an array of vividly coloured and sometimes rare secondary minerals. These include connellite, langite, atacamite, botallackite, brochantite, lavendulan and erythrite. The soft, wet, blue and green substances that coat the mine walls are amorphous gels that dehydrate and crumble to powder when removed to a dry environment. They are best left where they are. Fig. 3. Tankardstown Mine, Co. Waterford. The author is examining post-mining deposits of an amorphous copper-bearing gel. Mention should be made of the Croaghaun Hill beryl occurrence inland from the copper mines. In a small outcrop of conglomerate, one of many among the scrub, patches and sprays of slender, sky blue beryl prisms occur in a quartz matrix. Unfortunately, the rock is so tough it defeats even the largest sledgehammer. The … Read More
Jesse Garnett White (USA) “It is no measure of health to be well adjusted to a profoundly sick society” Jiddu Krishnamurti My Great Grandfather and his son both gave me some advice at a very young age. “Never trust anyone that won’t look you in the eye when they shake your hand” and “It’s OK to pick up hitchhikers while travelling the road”. These are all positive suggestions that have proved valuable both in the States and abroad. I’ve made a number of interesting decisions in my life. One I never thought I’d make was moving back to Alaska. I’ve told colleagues, dozens of friends, family members and myself, “I’ll never spend another winter in Fairbanks.”. Learning the lesson of ‘never say never’”, while travelling into the past and future simultaneously has been interesting to say the least. When a friend of 26 years heard the news, he said, “You can’t escape Covid-19, Jesse.” I completely blew that off and forged ahead. Since returning to Alaska, I’ve been fortunate to have worked with a lot of good folks, meet new friends, network, and travel around the interior and Alaska Range. I was blessed to work as a contract geologist at an open pit mine in both development and exploration roles, assist mom-and-pop miners with permitting, create an LLC, and work at what I consider the best pizza place in Alaska. Winter temperatures dipped below -50oF and snow depth at the cabin reached four feet in total. At the time of … Read More
Stephen Moreton (UK) The island of Ireland has much to offer the mineral collector, but is relatively unknown to most. This may in part be due to a lack of published information, although, for years, the troubles in the north also served to deter visitors for many years. This series of articles briefly summarises the principal mineral locations on a region by region basis. Fig. 1. The four regions of the island of Ireland. Fig. 2. Leinster in more detial. As the island is divided into four regions, Leinster, Munster, Connaught and Ulster (Fig. 1), which are in turn subdivided into counties, it seems appropriate to cover the island in this way. As the main ferry terminals for the Irish Republic are in Leinster many a trip to the country will start here. Leinster occupies the southeast region of the island and is the driest (or rather least wet) part of Ireland. Geologically, it offers the largest granite batholith in the British Isles, complete with metamorphic aureole, Carboniferous and Ordovician sediments and a scattering of basic igneous intrusions. County Wicklow dominates the mineral scene in Leinster. Fractures along the margin of the Wicklow granite have acted as conduits for much later mineralising solutions, giving rise to lead/zinc veins. These reach their best development in Glenmalure, Glendasan and Glendalough. Fig. 3. One centimetre spinel law twinned crystals of galena, from North Hero lode, Glendasan, Co. Wicklow. Fine schieferspar calcite and dark brown sphalerite have recently been found in Glendasan, while some … Read More
Jon Trevelyan (UK) If Yorkshire really is ‘God’s Own County’, then clearly the Almighty is an enthusiastic geologist. Just how lucky is the Yorkshire man who, on the same day, can see some of the best and most varied geology in the world, set out in glorious coastal and mountain … Read More
Richard M Haw (UK) Blue John is a unique variety of blue-purple banded fluorite. Hydrocarbons or oils have been deposited on some of the crystal surfaces while the mineral was forming. These oil layers are partly responsible for giving the stone an alternate blue and white banding, best seen when the stone is cut in section. It is not known to occur anywhere else in the world and is conﬁned to an area of about 1km³ of the Carboniferous “reef” limestones at Castleton in Derbyshire. Fig. 1. Old picture taken sometime in the 1870s, showing miners digging in the Old Dining Room, now part of the show caves. I have been involved with the public caverns here for a while and I am sure many of you have visited them. However, there are many people who have never even heard of Blue John, so the following article gives a general overview without intending to be too technical. The area Castleton is a small village located in Derbyshire’s “Peak District” between the cities of Manchester and Shefﬁeld. The village is dominated by the ruins of Peveril Castle that was built by the Normans to oversee lead mining in the area. The scenery around Castleton forms a dramatic backdrop and the rolling limestone hills end abruptly atthe vertical face of Mam Tor. Beyond and to the north are the gritstone moors known as the “Dark Peak” that eventually lead up to the two-thousand-foot-high plateau of Kinder Scout. Castleton and the surrounding area … Read More
Philip Dunkerly (UK) In A geological model for the alluvial gold environment (Part 1), the first part of this article, I discussed how alluvial gold is found and suggested a geological model for alluvial gold deposits. (Readers are recommended to have another look at that part to remind them of the model.) In this second part, I now turn to the nature of the gold itself. Fig. 1. Gold bullion bars of 400 troy oz. Fig. 2. Sites from around the world. Gulch gold Gulch gold is the coarsest that exists in any part of a river system. If nuggets (pieces of gold weighing more than 0.1g) are present, they will mostly be found in gulches (narrow ravines), provided suitable traps are present, such as irregular bedrock. In gulch alluvium, the vast majority of the gold will be found on, or in crevices within, the bedrock. Gulch gold is often coarse and angular and may contain silicate debris, especially quartz. As examples, gold from Victoria Gulch on the Klondike was described as “sharply angular”. In the Ballarat gullies, some enormous nuggets were found and Canadian Gully yielded nuggets of 50.4, 34.7 and 31.4kg. At Bendigo, White Horse Gully, a 17.8kg nugget (including some quartz) was found. (Interestingly, of a list of 92 Victorian nuggets, 34 came from localities specifically named “gullies”.) Finally, in the Sierra Nevada of California, most of the gold is from gulches or minor streams close to croppings. Fig. 3. Old hydraulicking operation of terrace gravels, note … Read More
Philip Dunkerly (UK) Mankind almost certainly first found gold when a yellow, glint from the bottom of a stream bed attracted the attention of one of our ancestors in pre- historic Africa. Ever since, the allure of gold – its colour, improbable density, malleability and scarceness – meant it has been prized, and great efforts have been made to accumulate it. Most ancient peoples venerated and coveted gold and used it for decoration, and empires used gold as a store of value and a medium of exchange. The Egyptians are known to have used gold as early as about 5000 BC, followed by many others, including the Romans, the Incas, the Spaniards and, of course, the Anglo-Saxon invaders of North America, Africa, Australia and New Zealand. Fig. 1. Spectacular Roman paleogravel workings at Las Medulas, NW Spain, now a World Heritage site. The mouth of one of the tunnels through which water was released from a header tank is visible in the shadow. Fig. 2. Panoramic view of Las Medulas, worked by sluicing using water brought through canals up to 60km long. Though gold was won from hard-rock deposits in ancient times, most gold until perhaps 1900 was won from riverbeds, and was traditionally called alluvial or placer gold. Prospecting for alluvial gold required relatively little equipment and always attracted hardy pioneers willing to forego the comforts of society in the hope of ‘getting rich quick’. The gold they found – if they were lucky – could almost instantly be … Read More
I sat down to read this over Christmas and what a good read it turned out to be. The appropriate word is ‘eclectic’ – because Measures for Measure is written for all us with an interest in the industrial history of Great Britain, and its impact on the landscape, economy, social history and culture. It’s a great read as it dots about linking places and ideas together, with the link always being the geology.
This is a lovely book – a glorious mixture of a beautiful coffee-table book and an academic treatise of the highest quality. But why microfossils? What is it about them that can create such strong feelings?
Dr Robert Sturm (Austria) Exploitation of gold deposits in the Hohe Tauern, in the Central Alps of Austria, has a long history: occurrences of this noble metal were explored for the first time about 2,000 years ago. Since the fourteenth century, the search for gold has been conducted on an industrial level, resulting in the production of 130km of tunnels and shafts, with the main centres of medieval gold production being the Gastein Valley, Rauris, Heiligenblut, Fusch and, later on, Schellgaden. In the second half of the fifteenth century, all of the gold found in the Central Alps was sold to Venice, but from the year 1501, the noble metal was exclusively used for indigenous minting and, therefore, all gold mines came under the archbishop’s control. Fig. 1. Map showing the position of the Hohe Tauern National Park (green) in Austria and the main locations of historical and current gold exploration. The economic zenith of gold exploitation in the Central Alps was reached in the middle of the sixteenth century. At this time, three families – the Weitmosers, Zolts and Strassers – dominated the mining industry in the Gastein Valley and in Rauris. In 1557, 830kg of gold (corresponding to about 27,000 ounces) and 2,723kg of silver were hauled from the mines. However, 50 years later, gold mining ceased completely. The main reason for this economic collapse was the total exhaustion of all lodes of ore that had been exploited in the Hohe Tauern until that time. Furthermore, only ‘visible’ … Read More
Ken Madrell (UK) Introduction Most visitors to the Cyclades islands will gravitate to the island of Santorini to see its stunning caldera and the magnificent sunsets from the northern town of Oia. The island is part of the Aegean volcanic arc formed by the subduction of the African plate under the Aegean Sea. About 3,600 years ago, the island suffered a violent volcanic eruption in which much of the rocks were removed, causing the volcano to collapse and produce the caldera. About 160km northwest of Santorini and also situated on the volcanic arc is the island of Milos. The island is a more peaceful alternative to the bustling crowds of Santorini and the rich volcanic soils are renowned for producing excellent wines and vegetables. Milos is a ‘must-visit’ island for any traveller with an interest in geology visiting this area of the Greek Islands. Fig. 1. Santorini. Northward view of the eastern caldera wall and rim. There are a number of designated Geo Walks on the Milos (see How to Explore the Island below). These can be up-loaded at https://www.milosminingmuseum.com/en/the-museum/miloterranean-geo-walks/. Readers may also wish to refer to these while reading the text of this article. The geology of Milos The oldest rocks are a basement of metamorphic rocks, such as schists, gneiss and quartzites of Mesozoic to Palaeogene ages (250 to 25Ma). The basement rock is overlain by Miocene to early Pliocene (25 to 5Ma) conglomeratic and calcareous rocks. The main character of the island we see today was formed … Read More
Benjamin Hayden Elick and Steven Wade Veatch (USA) The Cresson mine (Fig. 1) – situated between Cripple Creek and Victor in Colorado – was established in 1894 (MacKell, 2003). No one is certain who started the mine, but records show that two brothers, insurance agents, J R and Eugene Harbeck from Chicago, were early owners. After a hard night of drinking, they sobered up the next day and learned of their new acquisition (MacKell, 2003). The Cresson Mining and Milling Company was organised a year later, in 1895, to raise capital and operate the mine (Patton and Wolf, 1915). The mine continued operating through several leases with low but steady proceeds. Fig. 1. Early view of the Cresson mine, Cripple Creek, Colorado. Photograph date, circa 1914, courtesy of the Cripple Creek District Museum. The Cresson mine became profitable when Richard Roelofs, a known mining innovator, was hired by the Harbecks as mine manager in 1895. Roelofs wrote in an undated letterhead: I was a prospector, a leaser, a miner, an assayer and chemist, an underground shift boss, foreman, superintendent and then general manager of one to the greatest of Colorado’s mines” (Roelofs, n.d.). Roelofs (Fig. 2) was a newcomer to Colorado, as many were when the Cripple Creek gold rush ignited in 1891. He moved to Cripple Creek in 1893 with his wife Mabel. They had one child, Richard Jr, who was born on 19 August 1894 in Cripple Creek. Fig. 2. Richard Roelofs, manager of the Cresson mine. Photograph date, 1914, … Read More
I have stood several times in front of an (apparently) plain white, chalk cliff-face along with others, while Prof Mortimore discussed the implications of what we were seeing. And, every time, I left not just thinking but knowing this was the most fascinating piece of geology I had ever seen.
Robyn Molan (Australia) Fig. 1. The location of the excavations. In an article in the Australian Age of Dinosaurs Journal (Issue 6, 2008) I dubbed the period between 1984 and 1994 ‘a decade of dedication’, thanks to the persistence of an American-Australian team headed by palaeontologists Tom Rich and his wife, Pat Vickers-Rich. (Tom wrote an article for Deposits, entitled Tunnelling for dinosaurs in the High Arctic.) This was the decade that brought to the world the fascinating polar dinosaurs of south-eastern Australia and the eventual naming of three new dinosaur species – with a few other surprises along the way. Two hundred and twenty kilometres west of Melbourne, on the Otway Coast of Victoria, Australia, is a remote and little-known inlet. Set in a stretch of steep, rugged shoreline, this isolated cove is pounded by the Southern Ocean and blasted by Antarctic winds. Nearby, the world-renowned rocky sentinels, ‘The Twelve Apostles’ (see the cover of Issue 20 of Deposits), stand testament to the power of wave and wind, as they beckon tourists who travel the Great Ocean Road. Fig. 2. The rugged beauty of Dinosaur Cove. (Photo Ros Poole.) The excavation at Dinosaur Cove, as the inlet later became known, was the first major dinosaur dig conducted in Victoria. For several weeks each summer, the Rich family, and a crew of hardy volunteers, battled untold obstacles to wrestle fossils from the base of the cliff. It was gruelling, dirty and dangerous work, but subsequent scientific research on what was … Read More
Dr Thomas H Rich (Australia) Fig. 1. Location of the Liscomb Bonebed. (© Thomas Rich.) I have no idea what made me look up at that moment. But, when I did, I saw a flash of light reminiscent of the sun glinting off the wings of a flock of birds abruptly and simultaneously changing direction. However, the light was not from a flock of birds. Rather, it was from thousands of individual, fist-sized lumps of rock, together with lumps of half-frozen mud on the steep slope above me. They were glistening due to a film of meltwater covering them and they were simultaneously starting to roll because the tonnes of rock on which they lay had suddenly started to collapse and plummet down towards me on a journey that would end in the frigid waters just below my feet. At that moment, I was digging into permafrost at the base of the steep slope forming the left bank of the Colville River that flows across the North Slope of Alaska and terminates in the Arctic Ocean about 40km further downstream. (The North Slope is the tundra covered coastal plain in northernmost Alaska bordered on the north by the Arctic Ocean and 250km to the south by the east-west Brooks Range.) Like my companions, my efforts were directed towards recovering ‘polar dinosaurs’, at a locality named the Liscomb Bonebed in honour of the geologist who found it in 1961. Fortunately, the tonnes of mud and claystone that cascaded down the bank … Read More
There are many good guides the geology of the Lake District and this is no exception. However, this is first and foremost an illustrated guide to the region’s rocks and an introduction to the common rock types to be found, largely through the use of colour photographs.
Steven Wade Veatch (USA) Fig. 1, Robert Plews (32), with two daughters, Elizabeth (4) and Mabel (3) and his wife Janet (25), stand in front of their small home in Elkton, Colorado, one of the towns in the Cripple Creek Mining District. (Photo date circa 1899, from the S W Veatch collection.) This photograph, taken around 1899, shows my ancestors posing at their modest frame home, where they lived one step away from Cripple Creek’s gold rush world of cardplayers, whisky drinkers, and midnight carousers. The scene depicts my great-grandfather (Robert Pickering Plews), my great-grandmother (Janet Plews), and two of their daughters in front of their miner’s cabin, built from pine boards, on a hillside in the newly established mining town of Elkton, Colorado. My great-grandparents were from England. Two years after my great-grandfather married my great-grandmother, he left England – by himself – to build a better life in Cripple Creek’s goldfields for the family that he left behind. Robert Plews was a hope-chaser. He carried his dreams from England across the Atlantic and then 1,700 miles to the Front Range and Cripple Creek. He arrived in the gold mining district in 1897. Victoria was the Queen of England, William McKinley was the US President, and Marconi had sent his first wireless transmission. The Colorado Rockies meant a new chance for him at a place with unlimited opportunities. He went to work at the busy Elkton mine. After my great-grandfather established himself in the mining camp, he sent for … Read More
Steven Wade Veatch and Teresa L Stoiber (USA) The legend of “Genevieve”, a fossilised dinosaur not only made of stone — but also of gold — began on 3 July 1932. That was the day WK Jewett, owner of the London Mine near Alma in Colorado, stopped at the Antlers Hotel in Colorado Springs and made the official announcement of its unearthing. The story was picked up by the news services and word of the fantastic find spread through the scientific world like a prairie fire. The golden dinosaur was discovered by William White, 700 feet (213m) underground — deep in the London Mine (WK Jewett, 1932). Curiously, the miners had been using the creature’s nose as a lamp holder, not realising there was a ‘dinosaur’ (if that is what it was) there. White, a hard rock miner, believed at first he was looking at two stumps. In reality, it was a dinosaur lying on its back with its limbs at an angle of 75 degrees. Eager to retrieve it from its rocky tomb, miners blasted it out of rock at the 700-foot level of the London Mine with dynamite. The blast shattered the specimen. Bits and pieces of the dinosaur were hoisted to the surface, where curious crowds gathered to see the prehistoric monster. As the story goes, a geology professor at Colorado College, Robert Landon, travelled to Alma so he could examine Genevieve – an extraordinary record of a former world. The measurements he made revealed that the … Read More
As the author, John McManus, writes: “The East Neuk of Fife was blessed with a mineral resource that was relatively easy to access”. This resource was coal – the driver of the industrial revolution and, even before then, a crucial element to the area’s industrial development from medieval times (or even Roman times) to the late twentieth century.
Steven Wade Veatch (USA) While headed for the California Gold Rush of 1849, George Giggey (who was my great-great-grandfather) first made his way through the mountainous and untamed wilderness of what would later become Colorado. He was among a group of young men, who were determined to make a new life, fortune and future in the American West. After working in the Californian goldfields, he turned his attention to Colorado, where he prospected for gold for a while and then returned to the East. In 1865, George Giggey returned to Colorado with his family of ten children and built a homestead in the wilderness near what would become, in just a few years, the town of Caribou. The town developed around the Caribou silver mine that was discovered by Sam Conger in 1868. George Lytle, one of Conger’s partners, was from British Columbia and named the mine after his caribou hunting trips in Canada. By 1870, the Caribou Mine was in full production and was shipping ore down Coon Trail, to the nearby settlement of Nederland for processing. By 1872, the frontier town of Caribou built a much needed schoolhouse. Three of George Giggey’s boys attended Caribou’s first school session. They were: George Leon (my great-grandfather), who was 14 years old; Adelbert, age 7; and Charley, who was only 6 years old. I can feel the boy’s excitement when they took their seats in the one-room schoolhouse, with new furniture, blackboards, maps, globes and a new teacher – Miss Hannah … Read More
Dr Robert Sturm (Austria) This is the third of four articles on the quarries of the ancient world and later, and, in particular, the marble that was quarried there and the works of art made from it. The first is Mining in Ancient Greece and Rome and the second is Marble from the Isle of Paros – a tour of the ancient quarries. The ancient methods used An antique quarry is interesting because it is a place where raw material for buildings and sculptural works was extracted to specific sizes and shapes with the technical methods of that time. The mining techniques did not change very much from the earliest phases of human civilization until the end of antiquity, even though the methods used continuously improved over time. In ancient Greece, single blocks of the stone were separated by smashing several key holes into the rock wall, into which wooden wedges were driven. After that, the wedges were moistened, causing their expansion and the cracking of the block along the line of holes. For a better control of the rock fracture, long groves were carved into the blocks with iron tools, into which key holes were subsequently inserted. Alternatively, the blocks were completely split off from the rock walls by deep cuts in the rock and then separated from the ground using crowbars (Fig. 1). Fig. 1. Separation of single blocks of rock using a crowbar and leverage. Since archaic times, rock saws have also been used. In the Roman … Read More
Dr Robert Sturm (Austria) This is the second of four articles on the quarries of the ancient world and later, and, in particular, the marble that was quarried there and the artwork that was made from it. The first was Mining in Ancient Greece and Rome. Some introductory words In general, marble represents a coarse-grained metamorphic rock primarily consisting of the minerals calcite (CaCO3) and dolomite ((Ca,Mg) (CO3)2). The word ‘marble’ may be derived from the Greek term ‘marmaros’ (μάρμαρος), which means ‘shiny stone’. The earliest use of the rock dates back to the fourth millenium BC, when it was considered, for the first time, as appropriate material for the construction of buildings and the production of rather primitive sculptures. In the Classical era starting at the beginning of the fifth century BC, its use was subject to a remarkable increase, which, among other things, entailed the prevailance of this shiny material in ancient Greek architecture and sculptural art. At that time, marble was simply termed ‘white stone’ or ‘Pentelic, Hymettus or Parian stone’, thereby indicating its preferential origin from the quarries of Naxos, Paros and Mount Pentelicus. Although these mines attained extraordinary eminence in antiquity, marble was also exploited from the quarries of Eleusis, Tripoli, Argos, Selinus, Syracuse, Skyros and other places. Marble from Paros – a very particular stone Each marble originating from a local quarry is characterised by very specific features. Stone material from Mount Pentelicus is distinguished by its white colour and fine-grained texture, rather high … Read More
Khursheed Dinshaw (India) This the second of two articles on the Wieliczka Salt Mine in Poland. The first (Wieliczka Salt Mine of Poland (Part 1)) covered some of the highlights that can be seen there. This one covers some more of these features, but also deals with the geology of the site. The journey began in the Miocene period, which was about 13.5Ma, when the crystallisation of salt dissolved in sea water occurred. These salt deposits combined with rocks that normally accompany salt that occupied what was known as the Pre-Carpathian Sink. Subjected intensively to the tectonic process, these salt deposits shifted and folded. About 6,000 years ago, the local people of Wieliczka in Poland started to produce salt by evaporating salty water. In the thirteenth century, when the sources of the salty water were almost exhausted, they began to sink wells hoping to find salty water under the ground. In 1289, at the bottom of one of the wells, the first lump of the grey rock salt was found and that was the beginning of the Wieliczka Salt Mine. Today, the mine is divided into two portions. While its upper stratum is the block type, its lower stratum is of the stratified type; and visitors learn about salt, its excavation and types as they walk with their designated guides across chambers, pathways, tunnels, chapels and lakes. In the olden days, the equipment to transport salt from one level to another included wooden carts and trolleys. At Wieliczka, these are … Read More
Khursheed Dinshaw (India) The Wieliczka Salt Mine of Poland was included in the first UNESCO World Heritage list in 1978. It is also on the Polish List of Historic Heritage and, when visiting, provides an interesting way to get to know how salt has been mined underground for almost nine centuries. In the summer, almost 8,000 tourists a day visit Wieliczka, which has 500 tour guides and 400 miners maintaining the mine. After buying your ticket, you are allotted a guide who will take you around the mine. Patrycya, our guide, has been on the job for 20 years and we enthusiastically followed her to explore the beauty, material culture and historic heritage of the mine and its excavated complex. Fig. 1. Kinga – the patroness of the miners, along with other salt sculptures. We opted for the tourist route, which lets you explore chambers, galleries, chapels and lakes. The mine has been opened to the public with this route since the end of the eighteenth century and has more than 300km of galleries and almost 3,000 chambers. It is divided into nine floors at depths varying from 64m to 327m. We went down to the third floor, which is at a depth of 135m. To get to the first level, one has to walk down 380 wooden steps, but the walk is comparatively easy. There are a total of 800 steps that tourists walk in the mine and, after the tour ends, a lift takes you to the exit … Read More
Mark Wilkinson (UK) Practically everyone has an opinion on climate change by now, although for the vast majority of scientists, the weight of evidence is overwhelming – emissions of carbon dioxide and other greenhouse gases are causing climate change, sometimes referred to as global warming. One possible technology for fighting climate change is Carbon Capture and Storage (CCS) in which geology plays an important role. In fact, future generations of geologists may be employed searching for CO2 storage sites in the subsurface, rather than for the more traditional search for oil and gas. The aim of CCS is simple – to allow the continuing use of fossil fuels while reducing the emissions of greenhouse gases into the atmosphere. In the long term, the burning of fossil fuels will probably cease, but until we can rely on renewable sources of energy, we are stuck with these fuels as a cheap and reliable energy source. CO2 is emitted during many activities, including driving cars and heating homes, but the largest single sources are fossil fuel power plants, which generate electricity, followed by industries, such as steel works and cement plants. It is these that most research has been focussed on. And, in principle, the technology is simple – capture the CO2 from a source (such as a power plant; Fig. 1) before it gets into the atmosphere, then transport it to a suitable storage site and inject it into the ground where it will remain for tens of thousands of years. Fig. … Read More
Dr Robert Sturm (Austria) The Erzberg Mine is situated in the Austrian county of Styria. From a geological point of view, it belongs to the so-called greywacke zone, which represents a band of Palaeozoic metamorphosed sedimentary rocks intercalated between the Northern Limestone Alps and the Central Alps. The Erzberg Mine is the world’s largest deposit of the iron mineral siderite (FeCO3), which is mixed with ankerite (CaFe[CO3]2) and dolomite (CaMg[CO3]2). Due to this mixture of different mineral phases, the concentration of iron ranges from 22% to 40% and adopts an average value of 33%. The annual output amounts to about two million tons of iron ore, which is transported to blast furnaces in Linz and Leoben-Donawitz. According to current estimations, the ore reserves will allow mining activity for another 30 to 40 years. History of the Erzberg Mine There are lots of myths regarding the founding date of the iron mine on the Erzberg. According to the opinion of several scholars and a few written documents of dubious veracity, the mine was already established in the year 712, which would imply a use of the deposit by Slavic peoples. However, there exists better evidence that foundation of the mine took place in 1512, which was also the inauguration year of the Oswald church in the village Eisenerz. Fig. 1. The Erzberg Mine with its characteristic appearance, photographed from the north (Pfaffenstein). First documentary mention of the Erzberg Mine is from 1171. In the fourteenth century, the Reigning Prince of Styria … Read More
Dr Robert Sturm (Australia) The mineral, emerald, represents the green variety of the hexagonal silicate mineral beryl, which has the chemical formula Be3Al2Si6O18. Its colour may be interpreted as the result of the addition of vanadium and chromium ions into the crystal lattice. In fact, the etymology of the word “emerald” is derived from Vulgar Latin, where esmeralda (f.) or esmeraldus (m.) represented a commonly spoken variant of Latin smaragdus, which itself originates from the Greek smaragdos for “green gem”. From a historical point of view, the beginnings of emerald mining are in Ancient Egypt, where gem stones were already being unearthed in the fifthteenth century BC. The famous emerald mines located in Sikait and Sabara supplied Europe with precious minerals for more than thousand years. The gemstone was also highly sought after by the monarchs of India, Persia and the Ottoman Empire, such that it became an important merchandise. When South America fell under the domination of the Spanish crown, the European conquerors were confronted with a vivid emerald trade that ranged from Columbia to Chile and Mexico. In 1573, the Columbian Muzo mine was captured by the Spanish army and thereafter represented the most important production site in the world for emerald of gem quality. Nowadays, emerald is a highly esteemed gemstone achieving similar prices as equally sized diamonds. Due to the high demand, it is also produced synthetically. The process was developed by IG Farben in 1935, but satisfactory results were only achieved by Johann Lechleitner in … Read More