Prehnite is usually seen as translucent light green (sometimes darker green) gem of an oily appearance. It can also be a transparent and colorless material as found in the famed Jeffery Mine in Canada. Yellowish-green, brownish-green, gray, and white colors also occur. The best quality green prehnite is said to come from Fairfax County, Virginia.
Prehnite was the first mineral to be named after a person, the Dutch Colonel Hendrik von/van Prehn who is credited with discovering the mineral in 1774 at the Cape of Good Hope in South Africa.
There is no known synthetic production of prehnite. As for so many other gemstones, glass is a basis for faking.
Prehnite is sometimes misrepresented as green tourmalated quartz. Here's an interesting discussion on identifying the inclusions within prehnite.
Prehnite used to come mainly from the United States, but these days Australia, China, and South Africa are the main producers. Here's another good article on prehnite.
Image courtesy of irocks.com.
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