Check the listing for details. Raw Prehnite Specimen 3.3"/425 Grams. Condition: New. Listed at 12.00 USD. Prehnite is a calcium aluminum silicate mineral, typically pale green to yellow-green, with a vitreous to pearly luster and a botryoidal or granular habit. Significant sources include South Africa (notably the Kalahari Manganese Field), Australia, China, India, the United States (notably New Jersey), Scotland, and Namibia.