{"title":"Colemanite","description":"\u003cp\u003e\u003cstrong\u003eColemanite\u003c\/strong\u003e is a hydrated calcium borate, Ca2B6O11·5H2O, and one of the most prized species among borate collectors for its glassy, often gemmy crystals and razor-sharp cleavage. It forms as a secondary mineral through the alteration of borax and ulexite in arid, alkaline lacustrine (playa) environments, typically alongside gypsum, calcite, celestite and other evaporite minerals. Crystallizing in the monoclinic system, colemanite develops in an unusually wide range of habits — short prisms, blocky crystals, spiky bladed groups, twinned individuals and radial nodules — a diversity of form rivaled among minerals perhaps only by calcite. Hardness sits at 4.5 on the Mohs scale, with a specific gravity of 2.42 and perfect cleavage on {010} that gives cut fragments their characteristic brilliant sheen.\u003c\/p\u003e\u003cp\u003eThe species was first described in 1884 from the \u003cstrong\u003eHarmony Borax Works\u003c\/strong\u003e near \u003cstrong\u003eFurnace Creek\u003c\/strong\u003e in \u003cstrong\u003eDeath Valley\u003c\/strong\u003e, California, its type locality, and was named after borax magnate William Tell Coleman. California remains the classic ground for fine specimens: the \u003cstrong\u003eKramer district\u003c\/strong\u003e at \u003cstrong\u003eBoron\u003c\/strong\u003e (home of the historic \u003cstrong\u003eU.S. Borax open pit mine\u003c\/strong\u003e) produces the well-known spiky bladed crystals and, more rarely, prized red and yellow colored pieces, while the \u003cstrong\u003eBoraxo mine\u003c\/strong\u003e near Ryan and \u003cstrong\u003eTwenty Mule Team Canyon\u003c\/strong\u003e in the \u003cstrong\u003eFurnace Creek Mining District\u003c\/strong\u003e have yielded large, blocky, sometimes 15 cm single crystals. Nearby, the \u003cstrong\u003eCalico Mountains\u003c\/strong\u003e near \u003cstrong\u003eDaggett\u003c\/strong\u003e in San Bernardino County were an early 1880s source that helped launch the American borax industry. On the other side of the world, Turkey hosts the planet's richest colemanite reserves, with the \u003cstrong\u003eEmet\u003c\/strong\u003e, \u003cstrong\u003eKirka\u003c\/strong\u003e, \u003cstrong\u003eBigadiç\u003c\/strong\u003e and \u003cstrong\u003eKestelek\u003c\/strong\u003e deposits in the Kütahya, Eskişehir and Bursa provinces producing exceptionally large, gemmy, colorless-to-ivory crystals — including individuals reported up to 30 cm — along with striking twinned and zoned examples from the \u003cstrong\u003eKestelek mine\u003c\/strong\u003e. Iran's \u003cstrong\u003eQarah Gol Boron Mine\u003c\/strong\u003e in Zanjan Province is another notable, if less common, source for collector-grade material.\u003c\/p\u003e\u003cp\u003eBeyond the cabinet, colemanite is industrially important as a natural source of boron, historically the principal ore of borax until the 1930s and still valued for boric acid, borosilicate glass, fiberglass, ceramic glazes and fluxes. For collectors, though, its appeal lies in the contrast between the mundane industrial mineral and its finest crystallized specimens: lustrous, sometimes fluorescent, colorless-to-brown crystal clusters from Boron, Death Valley and Emet stand among the true classics of the borate mineral group, prized for their sharp forms, unusual twinning, and rarity in fine, well-crystallized condition.\u003c\/p\u003e","products":[{"product_id":"far-colemanite","title":"COLEMANITE – Lustrous White Crystal Geode, Emet, Kütahya, Turkey","description":"\u003cp\u003eA striking colemanite geode showcasing a dense cluster of milky-white crystals with well-developed faces, from the world-famous Emet borate deposit in Turkey. The crystals display good transparency to translucency and a lustrous surface, making this a strong mineralogical and display piece.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eMineral Data:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDimensions:\u003c\/strong\u003e 109 x 93 x 73 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 813 g\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProvenance:\u003c\/strong\u003e Emet Borate deposit, Emet District, Kütahya Province, Turkey\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"ITALMINERAL","offers":[{"title":"Default Title","offer_id":45605339070573,"sku":null,"price":89.0,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0693\/8027\/6333\/files\/IMG20251022181445.jpg?v=1786492026"}],"url":"https:\/\/www.italmineral.com\/collections\/colemanite.oembed","provider":"ITALMINERAL","version":"1.0","type":"link"}