Borate minerals occurrence

HEL/MUH] Helvaci, C., Occurrence of rare borate minerals veatchite-A, tunellite, teraggite and cahnite in the Emet borate deposits, Turkey, Miner. Deposita, 19, (1985), 217-226. 

Occurrence. Niobium and tantalum usually occur together. Niobium never occurs as the metal, ie, ia the free state. Sometimes it occurs as a hydroxide, siUcate, or borate most often it is combiaed with oxygen and another metal, forming a niobate or tantalate ia which the niobium and tantalum isomorphously replace one another with Htde change ia physical properties except density. Ore concentrations of niobium usually occur as carbonatites and are associated with tantalum ia pegmatites and alluvial deposits. Principal niobium-beariag minerals can be divided iato two groups, the titano- and tantalo-niobates. 

Occurrence.—Small quantities of ammonium salts are widely distributed over the surface of the earth and throughout the ocean. They are present in the Stassfurt deposits. The sulphate and chloride have been found in the neighbourhood of active volcanoes, and the borate is present in the boric-acid soffioni. A mineral called struvite, MgNH4P04, is a product of the decomposition of animal excrement in the soil. 

Natural occurrence, minerals, and ores. Boron is extracted from borate minercds such as borax or tincal, kernite, colemanite, and ulexite occurring in evaporitic brine deposits located in desert areas worldwide such as in the USA in Boron, CA and Turkey. 

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