Mineral Gallery
Olivine
Written by Boss Tambang Tuesday, 01 December 2009 23:44
Olivine is magnesium-iron silicate, a common mineral in the basalts and other mafic igneous rocks that make up the oceanic crust. It is found in all compositions between pure magnesium silicate (forsterite) and pure iron silicate (fayalite), and olivine composition is often given as a number from zero to 100, where 100 is pure...
Opal
Written by Boss Tambang Tuesday, 01 December 2009 23:43
These four images are the same “Christmas tree” opal, rotated in different positions to show the play of colors. The stone is about 5 millimeters across, mounted in white gold as a stud earring. The whole rainbow can be seen in these scans. Opal is a delicate mineral, hydrated silica or amorphous quartz. The mineral includes a fairly large amount of water...
Plagioclase Feldspar (Labradorite)
Written by Boss Tambang Tuesday, 01 December 2009 23:40
This specimen shows the peculiar form of schiller called labradorescence. The left image is the back side, unpolished, and the right image is the polished side. Not all labradorite displays this effect, but when it shows up you know it for sure. That’s worth knowing, because otherwise the feldspar minerals can be very difficult to...
Pyrite
Written by Boss Tambang Tuesday, 01 December 2009 23:39
Pyrite, iron sulfide, is a common mineral in many rocks. Here it occurs in relatively large crystals associated with quartz and milky-blue feldspar. It is the most important sulfurcontaining mineral. Pyrite resembles gold slightly, but gold is heavier...
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