Very down-to-earth Vasquez rocks portray the surface of alien planets for the media

Deborah Painter (USA) They have become associated with stark alien or other-dimensional landscapes since the 1960s, when the popular American television programme Star Trek used them as dramatic backdrops in two episodes, “Arena” and “Friday’s Child”. Prior to that, the Vasquez Rocks of Agua Dulce in California were a favoured location for American Western programmes, such as Branded, Cheyenne, Zorro and The Adventures of Champion, as well as motion pictures like One Million BC (1940) and Apache (1954), when rocky areas with hiding places, wide overlooks and an overall arid, rugged look were needed. More recent films and television programmes tend to exploit their odd appearance (Star Trek IV: The Voyage Home (1986), Army of Darkness (1993) and John Carter (2012)). Some films with no fantasy elements also use the rocks as a backdrop, one example being the family “road” comedy, Little Miss Sunshine, released in 2006. Fig. 1. The much-photographed side of the Vasquez Rocks pinnacle and main film staging area. (Photo: Michael Ramsey.) In fact, the Vasquez Rocks now have the distinction of being an overexposed outdoor location simply because of their proximity to the big city of Los Angeles’ filmmaking industry, hence their presence in scores of films, television programmes and music videos. Only about 64.5km from Los Angeles, the Vasquez Rocks are off State Highway 14, between Acton and Santa Clarita in California, USA and can be seen from Highway 14. The signs will direct the motorist to the exit that leads to the Vasquez Rocks … Read More

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Pistol shrimps: How to recognise them in the fossil record

Matúš Hyžný (Slovakia), Andreas Kroh (Austria), Alexander Ziegler (Germany) and John WM Jagt (The Netherlands) Alpheid shrimps, colloquially referred to as “pistol shrimps”, exhibit a remarkable anatomical adaptation. These tiny marine crustaceans use their enlarged and highly modified claw to ‘shoot’ at their prey – hence their name. It is astonishing that the snapping claw evolved at least 30 million years ago. How do we know that? Because the fossils tell us. Fig. 1. Habitus (body form) of alpheid snapping shrimps, exemplified by the extant species Alpheus thomasi from the Caribbean Sea. (Photo: Arthur Anker.) The famous snapping claw Alpheid pistol shrimps represent a super-diverse group of benthic marine crustaceans (that is, living on the bottom of the sea, including the sediment surface and some sub-surface layers). There are more than 600 living species, nearly half of which belong to the genus Alpheus. Its representatives possess a snapping claw, a multifunctional tool used for various types of behaviour such as aggression, warning or defence, as well as for hunting prey. Although snapping claws evolved independently several times within various decapod crustaceans, only in pistol shrimps did this organ attain true perfection. Fig. 2. Pistol shrimps ‘shoot’ with an enlarged, modified claw. (Photo: Arthur Anker.) The process of snapping involves a cracking sound reaching up to 210 decibels, one of the loudest produced by any animal. This noise originates from the collapse of a cavitation bubble in front of the claw, which, in addition, is accompanied by a short flash of … Read More

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Mysterious blue orbs of K2 granite

William Wray (USA) K2 granite is found near the base of K2, the mountain it is named after, in the Himalayas from a rarely visited site. K2, also called “Mount Goodwin Austen” is the second highest mountain in the world, rising to 8,611m (28,253 feet). K2 got its name from the British surveyor TG Montgomerie. The “K” comes from the Karakoram mountain range and the “2” means that it is the second tallest peak recorded. Fig. 1. An oval cabochon made from K2 granite found on K2, a mountain between Pakistan and China, revealing several bright blue azurite stains. The blue azurite stains formed after the granite cooled and hardened. (Photo by the author. Specimen from the William Wray collection.) K2 granite has impressive splashes of blue circles or orbs on its surface. The blue circles are azurite inside of white K2 granite rock. The white granite is fine-grained and composed of the minerals: quartz, feldspar, muscovite and biotite. The azurite stained parts of the granite, making blue dots, which range from a couple of millimetres to about two centimetres. Azurite has a relative hardness of 3.5 to 4 on the Mohs hardness scale, but assumes the hardness of the white granite, because the azurite is only a stain. The azurite formed after all the other minerals in the granite had cooled and hardened. With a hand lens or microscope, azurite spheres reveal that the azurite appears along the edges of mineral grains, in tiny fractures in the granite, and … Read More

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La Gomera: A short geological guide

Ken Madrell (UK) The island of La Gomera has an area of 370km2, it is 25km in diameter, has a maximum altitude of 1,487m (Alto Garajonay) and is situated approximately 40km west of Tenerife. Unlike the other Canary Islands, La Gomera has experienced a long and continuing eruptive break and is in a ‘postshield erosional stage’. Carracedo and Troll (2016) describe this as the stage when active volcanism has ceased, and erosive and denudational landforms are predominant (p. 39). The submarine base of the island shows that it rests on a shallower ocean bed than the surrounding islands. The emerged land mass is semi-circular in shape, with a radial drainage pattern from its centre near Alto de Garajonay. The dating of the island has proved problematic, as some of the earlier measurements placing its age between 15 Ma and 19 Ma have since proved to be inaccurate. More reliable estimates now put its age at between 10 and 11 Ma. Fig. 1. Roque Argando viewed from Lomo de la Mulata. La Gomera’s general stratigraphy comprises of three main rock sequences: (1) A Miocene basaltic shield, including a basal plutonic complex (that is igneous rock formed by solidification at considerable depth beneath the earth’s surface); (2) A nested felsic (that is, igneous rocks that are relatively rich in elements that form feldspar and quartz) stratovolcano (which is built up of alternating layers of lava and ash); and (3) The youngest Pliocene volcanism. Fig. 2. Sketch map of La Gomera, showing the … Read More

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Volancoes of Big Island, Hawaii (Part 1)

Dr Trevor Watts (UK) We (my wife Chris and I) enjoyed our fourth visit to Big Island Hawaii in May 2013 so much that we decided to return to the same places in October 2014. We were hoping to see similar events and activities, which we had found particularly interesting and accessible over the years. Every time we visit, something changes or isn’t possible, but this time was a little more changeable than most. The intervention of three ladies altered a few of our plans – Iselle, the hurricane that visited the southeast of Big Island two months before we arrived; Madame Pele, the Hawaiian Goddess of the Volcano; and Ana, the hurricane that hit the area during our stay. The three interventions illustrate the simple fact that we and our little plans have to be adaptable and show that some of the great locations will be discussed in these articles and will be missed if you only make one visit. This is the first of three articles on Big Island in Hawaii. In them, I will talk about the major highlights of our visit in connection with the volcanic activity of this wonderful island. This first part will mostly illustrate the different volcanic concepts that need to be understood to appreciate what can be seen, and will also provide a general background to the location and the significant summer 2014 flow towards Pahoa. About lava Traditionally, lava is described as pahoehoe or a’a. These are taken to mean ropey … Read More

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Fossil folklore: Molluscs

Paul D Taylor (UK) The final article of this series on fossil folklore focuses on molluscs, excluding the ammonites, which were covered earlier (see Fossil folklore: ammonites in Deposits, Issue 46, pp. 20–23). Molluscs are second only to arthropods in the number of species living today and the resistant calcareous skeletons possessed by the majority of species accounts for their extremely rich fossil record. Most fossil molluscs belong to one of three major groups – bivalves (oysters, clams and so on), gastropods (snails and slugs) and cephalopods (ammonites, belemnites and so on). Added to these are a few minor groups, such as the monoplacophorans and scaphopods (tusk shells). Fossil molluscs are usually recognisable instantly as belonging to this phylum because of their close similarities with the shells of familiar species of modern molluscs. Some, however, are not quite so straightforward. These are more likely to have been the sources of fanciful stories about their origins and significance. Among the more obscure ancient molluscs are those dubbed ‘difficult fossils’ by Martin Rudwick in the context of the early history of palaeontology and doubts over the origin of fossils. They include the solid internal casts (steinkerns) formed by lithification of sediment enclosed by the shell and subsequent loss of the defining shell itself. In addition, there are some mollusc fossils – notably belemnite guards – that bear little resemblance to any living species, adding to their enigmatic nature. Belemnites: thunderbolts and Devil’s Fingers The first fossils I ever came across were belemnites … Read More

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Armboth Dyke, Lake District

Mark Wilkinson (UK) The Armboth Dyke makes a good half day geology excursion in a scenic but quiet part of the UK Lake District. Parking is on the west shore of Thirlmere, in a pay-and-display car park accessed by the narrow road that winds around that side of the lake (Grid reference NY 305 172). The car park is in an excellent setting, with direct access to the wooded lake shore, and would be a great place for the non-geologically minded to wait while you venture onto the adjacent hill. It is probably worth noting at this point that the dyke itself is mostly exposed on rather featureless rolling moorland at around 400m above sea level (Fig. 1), and might not be a good place to visit in thick mist, unless you are very confident with a map and compass. If you happen to be in the business of teaching students to make geological maps, this site makes a great practise day, without too many problems of recognising weathered rocks in the field. Fig 1. Moorland with the dyke just visible as a slightly lighter patch of rock below the red arrow, where the edge of the dyke is exposed. University of Edinburgh students for scale. So, assuming you have decent weather, leave the car park and take the path uphill from the west side of the minor road, a few metres to the north of the car park. The path is steep-ish, and can be slippery if wet, so … Read More

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Recollecting rocks and minerals

Malcolm Chapman (UK) Collecting is natural. We all do it to a greater or lesser degree and what we collect is motivated by many factors including value and the appeal to the eye. Rarity is often a factor, as is cost, and interest can be awoken by someone you are related to, a teacher or a friend. So how did I become involved with collecting rocks and minerals? It was a television programme called Serendipity, which was broadcast about 35 years ago. Not long before (and at great cost), I bought some amber jewellery. And, then, there on the TV, was a young lady walking along the beach at Aldeburgh and picking up stones – not many, considering the number surrounding her, but a few handfuls. She was collecting amber and she had gathered an admirable collection for free, which would have made most people envious. The grey matter started working. Aldeburgh was some distance away, but, close at hand, was the beach at Sheerness and I knew about longshore drift…. By the action of wind and tide, stones on the east coast work their way south and north-facing beaches, like Sheerness, gather the stones moving from north of that point. Therefore, I decided that amber should be on Sheerness beach. I had never studied the stones on a beach before, but I believed that there could be many glamorous stones that I could find such that I envisioned making jewellery with them, mostly pendants. My experience was that they … Read More

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Henry VIII’s lost ruby: The ‘Regale’ of France

Steven Wade Veatch (USA) Glittering jewels, precious metals and religious relics – ranging from a spine from the Crown of Thorns to a twig from the Burning Bush, and sundry relics of saints – were important to all medieval monarchs as physical symbols of power, pomp and religious expression. King Henry VIII (1491-1547) of England was no different and had one of these venerable objects – a ruby. Fig. 1. Henry VIII, The king can be seen sporting several jewels in this 1531 painting. Henry prized the French Regale, a ruby fashioned into a cabochon. It remained in Henry’s private collection until he died at the age of 55 in 1547. Image public domain. A ruby (Al2O3) is a gemstone and a variety of the mineral corundum (aluminium oxide). It is one of the hardest minerals on Earth (9.0 on the Mohs mineral hardness scale of 10) and ranges in colour from pink to blood-red. Traces of the element chromium cause the red colour to bloom in rubies. The Latin word for red, ruber, is the basis for its name. The other variety of gem-quality corundum is sapphire. The ruby is extremely rare and considered the king of the gemstones, with its magnificent colour and exceptional brilliance. Louis VII (1120-1180) became the first King of France to visit England when he made a pilgrimage in 1179 to St Thomas Becket’s shrine at Canterbury. He spent the night there, and made several offerings, including the ‘Regale’, considered the finest gem in … Read More

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Mineral colours

Stuart Adams (UK) One of the main attractions of a mineral specimen is its colour and this is often due to the chemical composition of the mineral. Commonly, transition metals (nickel, chromium, copper and so on) give rise to colours that are attractive to the eye. The mineral in question absorbs certain wavelengths of the visible light spectrum and emits only those that you can see. For instance, the unmistakable blue of dioptase (a hydrous silicate of copper) is due to the presence of copper. Fig. 1. A specimen of opal from many collection, about the size of a clenched fist. This is called “Mexican Fire Opal”. It is a;sp called “Jelly Opal”. Malachite (a mixed copper hydroxide/carbonate) has a characteristic green that is also due to copper. The atomic structure of this mineral, which is totally different from dioptase, illustrates how colour does not always indicate composition. Fig. 2. Close up of Fig. 1. This piece has depth and good colour. The size is about as big as the tip of one’s thumb. It is easier to understand why they call this “Fire Opal” or “Jelly Opal” with this view. But what gives rise to the colour of opals? These hydrous silicas contain virtually no trace elements yet display colours ranging from the reds of the Mexican Fire opals through to the blues of the Australian opals. So, why should a substance of such simple composition display such attractive hues? Fig. 3. A good fist-sized specimen from my collection. It … Read More

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Guide to minerals: Selenite

Jerrod Gallup (USA) I got this selenite crystal at the first Pebble Pups meeting I attended. As a result, I researched this crystal and found lots of interesting facts, in particular, that it was very unique. This particular crystal was found in Oklahoma in 1970. In fact, you can go to Oklahoma and find selenite crystals on the salt plains there and the hourglass-shaped selenite crystals are only found at this location. It is also the Oklahoma State Crystal. Fig. 1. Selenite crystal from Oklahoma.Image by Jerrod Gallup, 2013. Facts on fileFormula: CaSO4 2H2OCategory: Sulphate mineralCrystal system: MonoclinicMohs hardness scale: 2Lustre: PearlyStreak: WhiteColour: Can be green, brownish, yellow, greenish, gray green or gray whiteSelenite crystals are found in: Mexico and OklahomaHaiku An orange crystal Formed by nature’s loving hands In the soft brown ground. About the author Fig. 2. The author, Jerrod Gallup, is on the left. His cousin, Noah Paul, is on the right. They are collecting rock and mineral specimens in one of the areas of Colorado that were recently burned in a fire. Jerrod Gallup (age 9) is a third grader at Columbine Elementary School, Woodland Park, CO. He belongs to the Lake George Gem and Mineral Club. Further reading http://en.wikipedia.org/wiki/Selenite_(mineral). http://www.statesymbolsusa.org/Oklahoma/stateCrystalOklahoma.html.

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Mineral classics from Wales

Tom Cotterell (UK) Ask any mineral collector to name a classic mineral locality or region in Britain and they will probably think of Cornwall or Devon, perhaps Weardale in Co Durham, or even the Caldbeck Fells or the West Cumbrian iron mining district in Cumbria – but probably not Wales. This is not to say that Wales has no classic minerals, but is perhaps a reflection of collecting habits and the preference for large, brightly coloured crystals. Wales has a long history of mining dating back to, at least, the Bronze Age, but, unlike some other regions, there does not appear to have been a desire by miners to extract mineral specimens for sale. Indeed, a network of mineral dealers, as was clearly present in Cornwall during the nineteenth and twentieth centuries, was totally absent in Wales. One factor is that the establishment of a National Museum in Wales occurred relatively late (in 1907) and did not open to the general public until the 1920s. Before this, there was no central repository for specimens collected in Wales and, consequently, mineral collections with historical significance are rare in the Principality. The university colleges founded during the 1870s and 1880s built up their own academic collections. Earlier still, the Royal Institute of South Wales (founded in Swansea in 1835), established geological collections, but its focus appears (from what records remain) to have been wide ranging and not specific to Wales. Therefore, during the heyday of mining in Wales, the lack of one … Read More

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Crystals and minerals of the London Clay

Bob Williams (UK) I developed a passion for crystals while collecting fossils. To me, crystals don’t have to be fancy, rare or expensive to be of immense interest. Even a good specimen of the commonly encountered “fools gold” (iron pyrite, more technically referred to as iron sulphide) will be of great interest to me. I live in south-east England, which is perhaps not the best place in the country for collecting interesting crystal specimens. However, I have a special interest in a geological deposit known as “London Clay” that is highly fossiliferous and includes fossils of crabs and lobsters. Many people will not associate this deposit with interesting minerals, but this would be to underestimate its potential. Fig. 1. London Clay, Isle of Sheppey, Kent. Crystal groups display the geometry of the crystal structure that is associated with a particular mineral and their forms can vary a great deal. The atoms, from which a substance is built, combine into structures known as “unit cells”. The atomic structure of a unit cell is then identically repeated, forming assemblies that give rise to the final crystalline form (that is, the mineral itself). Some compounds produce small, crystalline structures while others can produce individual crystals that are massive in size and striking in overall appearance. Amethyst is a good example of this and is, perhaps, the most familiar and most commercially available mineral of this type. A closer look at the crystal structure of any mineral will reveal objects of such incredible, geometric … Read More

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Rose and blue quartz

Steven Wade Veatch (USA) Quartz (SiO2) is a common mineral found in all three classes of rocks (igneous, metamorphic and sedimentary), in many environments and in a range of colours. However, rose and blue quartz are less common than some of the other varieties. This article discussed these two extraordinary minerals. Rose quartz Rose quartz has a pale pink to rose-red colour, thought to be caused by trace amounts of titanium, which absorbs all colours except pink. In a laboratory experiment, samples of rose quartz from several localities were carefully dissolved in acid. The remaining insoluble residue consisted of thin microscopic fibres, which may also be responsible for the colour of rose quartz. Well-formed rose quartz crystals are rarely found in nature, but when they are, they are generally found in massive chunks associated with pegmatites (Fig. 1). Fig. 1. This large rose quartz specimen was found at the Devil’s Hole Mine (owned by Tezaks), about a mile from the town of Cotopaxi, Colorado. (Photo © 2007 A Schaak.) The term pegmatite refers to exceptionally coarse-grained crystalline granite. Since rose quartz is cloudy, it is not popular as a faceted gem, but it is commonly made into cabochons (Fig. 2), rounded into beads for necklaces or carved into various objects. Fig, 2. A cabochon pendant from the same rose quartz near Cotopaxi. (Photo © 2007 A Schaak.) It has been named as South Dakota’s official state mineral. Here, rock hounds have a good chance of finding specimens ranging from shades … Read More

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On the origin of agate: A 300-year-old enigma

Terry Moxon (UK) Quartz has been estimated to occupy around 12% of the earth’s crust and can be found in many forms, ranging from the massive, clear crystals of quartz and amethyst to the microcrystalline quartz that is to be found in jasper, agate, chalcedony, chert and flint. World-wide, the distribution of agate is not equal, but it can be found in every continent and probably exists in every country. However, only three countries extract enough agate for world export: Botswana, Brazil and Mexico. Fig. 1. Empty gas cavities and agate amygdales in a block of Isle of Mull basalt. (Scale bar = 2cm.) Agate is most frequently found in fine-grained, igneous rocks filling gas cavities (Fig. 1), but it can also be found in sedimentary limestone hosts (Fig. 2) and fossil wood (Fig. 3). The most common agates are the wall-lining and horizontally banded types (Figs. 4 and 5 respectively). Rapid identification of agate in the field relies on the natural translucency of a fractured sample, but final confirmation is supplied by examining a thin section under a polarising microscope (Fig.6). Agate and chalcedony show a fibrous structure, whereas the quartz in flint, chert and jasper is generally granular. Granular quartz can demonstrate regular banding, but this is not agate (Fig. 7). Nevertheless, it is the colours and rhythmic banding that makes agate the most recognisable of all gemstones. Fig. 2(a) and (b) show agate in limestone from Tepee Canyon, South Dakota, USA. Note that both agates are surrounded … Read More

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Collecting minerals around the world

 Trevor Devon (UK) At some time, I suppose we have all collected rocks or minerals when we were travelling to new places, mostly as mementos, but nothing quite beats the buzz of collecting specific minerals from classic locations with like-minded colleagues. This type of collecting implies you know something of the geology and mineralogy of the location, what sort of rock to explore (often with a sledgehammer to start with) and what colour and shape the minerals are likely to be found in. Of course, it helps to travel with colleagues who have been there before and can show you what to look for. That is one of the reasons why I joined the Sussex Mineralogy and Lapidary Society (SMLS) a few years ago. Fig. 1. Behind the scenes at the mineralogy department of the Royal Ontario Museum, Toronto. Since 1980, SMLS has conducted trips to many parts of the world, including the USA and Canada, India, Namibia in Africa, and several countries in Europe. Such trips usually attract around a dozen or so participants and are often organised with a bit of tourism so that non-mineralogical spouses can join in. I have been fortunate enough to join recent SMLS trips to Cornwall, Isle of Skye, India, the South of France, the USA, Canada, the Caldbeck Fells in Cumbria, and Bulgaria. Perhaps I should start with the basic question of why I collect minerals. First of all, I think some of us are born collectors – for example, I collect … Read More

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Guide to minerals: Amethyst

Steven Marquez (USA) Amethyst is the violet to purple variety of quartz. It is often associated with albite and orthoclase in pegmatites. Fine specimens of amethyst can be classified as semiprecious gemstones. This specimen was found in Cripple Creek Colorado, as a near surface deposit on the David Leighton gold mine, owned by Steven Wade Veatch across from the hardware and grocery store on Teller County 1. The short, stubby amethyst crystals formed gas pockets in a hot, welded ash deposit that once covered the landscape of Cripple Creek. Amethyst is also mined in great quantities from the state of Minas Gerais in Brazil. A deep purple amethyst is commonly found in Uruguay. The colour purple is a royal colour, which is why amethyst is often used in jewellery for kings and queens. It was highly valued by Egyptians and the ancient Greeks believed that it protected against intoxication. Amethyst is the birthstone for February. Fig. 2. Note the faint crosswise striations on the surface of the amethyst crystal. This is one of the diagnostic features of quartz. The specimen is from the Steven Veatch collection. Photo by Steven Marquez. Facts on fileChemical formula: SiO2Composition: silicon dioxide; the colour is caused by iron or manganese impuritiesColour: purple, greasy lustreStreak: whiteHardness: 7Crystal system: hexagonalTransparency: transparent to translucentSpecific gravity: 2.65Lustre: vitreousCleavage: noneFracture: conchoidalTenacity: brittleGroup: silicates, tectosilicatesHaiku Brilliant purple Never ceasing to amaze Glowing like the stars About the author Fig. 2. Steven Marquez, seen working on the curation and cataloguing of the … Read More

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