Prehnite Natural 8X10mm Freeform Cut - 15-16 Inch Donut When the level of iron

When the level of iron oxide is high

and is a result of trace amounts of copper or chromium

red and magenta hues

while the amount of Iron in the stone varies its shade of purple

Prehnite Natural 8X10mm Freeform Cut - 15-16 Inch Donut When the level of ironPrehnite 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.