Prehnite Introduction:Prehnite is a silicate mineral. They usually appear in cavities in igneous rocks, and sometimes they can also be seen on stalactites. The color of prehnite ranges from light green to gray, and there are also white, yellow, red and other tones, but the most common one is green, and yellow is extremely rare and precious. Both transparent and translucent are available. Their shapes include plate-like, flaky, grape-like, kidney-like, radial or massive aggregates, etc. Good-quality prehnite can be used as a gemstone, and this gemstone is called Cape Emerald.