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Saturday, March 28, 2009

Chlorite in Quartz

This is a very interesting piece of chlorite in quartz specimen:

The layered inclusions on the face of the crystal look like that of a thumprint, check out the zoom up below:

Chlorite inclusions are very common in alpine-type environments, and generally occur in fissures and pockets inside igneous and metamorphic rocks, and in sedimentary rocks that are rich in clay minerals. "Chlorite" is actually the name for a group of phyllo-silicates (sheet-silicates), minerals of mica-like appearance. The name refers to the very common green color, although chlorite minerals do not have to be green.

Chlorite minerals form at low to moderate temperatures. Often quartz from alpine-type clefts has a chlorite "icing" on the crystal surface, giving them a rough and dull look, because the crystals started to grow at high temperatures, and when their growth slowed down at lower temperatures, chlorite formed in the pocket and settled on the crystal faces.

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