Crystals that grow to form long thin needles are said to have an acicular or needle-like habit. Related Articles: Mineral collecting in SlovakiaTiny bubble theory of Lake Superior agate formation (Part 3): Non-silica minerals and colours in agatesCopper infused agates from the Wolverine #2 Mine in Keweenaw County, MichiganCritical minerals (Part 1): A collector’s guide to Earth’s most strategic resourcesCritical minerals (Part 6): Nickel – a mineral of beauty, industry and strategic value« Back to Glossary Index