Prehnite Natural 8X10mm Freeform Cut - 15-16 Inch laborday_5 At that time yellowish gems

At that time yellowish gems were called "topaz" in many parts of the world

orthorhombic crystals or in massive form

and comes in a range of other colors

reddish to browns

Prehnite Natural 8X10mm Freeform Cut - 15-16 Inch laborday_5 At that time yellowish gemsPrehnite was the first mineral to be named after a person: its discoverer, Dutch Colonel Hendrik Von Prehn. Von Prehn discovered the stone in South Africa in 1774. Prehnite is translucent to transparent, in colors from light green to yellow green to olive, with occasional inclusions of Black Tourmaline that crisscross the stone in fibrous patterns. It is a phyllosilicate composed of silicon, calcium and aluminum with trace amounts of iron.