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staurolite penetration twin

Staurolite: Fairy Crosses With Storied Legacy

By Jim Brace-Thompson Many minerals crystallize in patterns that resemble across, a shape that has held special significance in Christian and pre-Christian civilizations. Two minerals...
Pistachio green epidote

Eye on Epidote

By Jim Brace-Thompson Calcium aluminum iron sorosilicate Ca2Al2(Fe3+, Al)Si3O12(OH) Epidote is one terrific silicate mineral for display. It produces well-formed prismatic crystals that are long, slender, striated...