Wood TinThis bulbous rock is dominated by the mineral cassiterite, a simple tin oxide mineral that i
Wood TinThis bulbous rock is dominated by the mineral cassiterite, a simple tin oxide mineral that is humanity’s primary source of tin. In fact, the Greek word for tin is “kassiteros”. The mineral can be found in a crystalline form, where it forms dark blades, but if it grows sequentially around a central core as in this rock it can create a banded structure that is also cut into collectible gems. This particulary variety is also called wood tin.This sample comes from England, where it formed from a crystallizing igneous body as is common for this phase. The crystalline version commonly forms in pegmatite bodies along with other large crystals, but this kind likely formed along some sort of fracture that allowed hot fluids to come out of a single point sequentially. As more water came out of the crack and cooled, it precipitated a new layer. This mineral is also likely intergrown with other minerals including, hematite, cristobalite, and chalcedony, giving it the reddish color.-JBBImage credit: James St. Johnhttps://flic.kr/p/JxoPm2References:http://www.gemselect.com/gem-info/cassiterite/cassiterite-info.phphttp://www.mindat.org/min-917.htmlhttp://webmineral.com/data/Cassiterite.shtmlhttp://www.minerals.net/mineral/cassiterite.aspxhttp://www.minsocam.org/ammin/AM62/AM62_100.pdf -- source link
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