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Spurrite
Spurrite is a white, yellow or light blue mineral with monoclinic crystals. Its chemical formula is Ca5(SiO4)2CO3.[4] Additional recommended knowledgeSpurrite is generally formed in Contact metamorphism zones as mafic magmas are intruded into carbonate rocks.[5] Spurrite's space group is P 2/a. It is biaxial with a birefringence of 0.0390-0.0400, giving second order red interference colors when viewed under crossed polarizers in a petrographic microscope.[6] The calcium is in six-fold coordination with the oxygen, the silicon is in a four-fold coordination with the oxygen and the carbon is in two-fold coordination. One unique characteristic of spurrite is that it actually abides by two twin laws. Polysynthetic twinning can occur along its (001) and another type of twinning can occur parallel to its optical axes.[5] Discovery and occurrenceSpurrite was first described in 1908 for an occurrence in the Terneras Mine, Velardeña District, Durango, Mexico. It was named for American economic geologist, Josiah Edward Spurr (1870-1950).[2] In addition to its type locality, spurrite has been reported from Riverside County, California; Luna County, New Mexico; and from the Little Belt Mountains, Lewis and Clark Coounty, Montana. It is also found in Ireland, Scotland, New Zealand, Turkey, Israel, Japan and Siberia.[1] Cement manufacture contaminantSpurrite forms as contaminating spurrite rings on the walls of cement kilns during the production of Portland cement.[7]
References
Categories: Silicate minerals | Carbonate minerals |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Spurrite". A list of authors is available in Wikipedia. |