Prehnite is a hydrous inosilicate of calcium and aluminum. it was discovered in Cape of Good Hope, eastern Cape Province in South Africa in 1788 and named in honor of Colonel Von Prehn.
The main producers are Mali, USA, Australia, China and Canada. It is generally green, sometimes green-yellow and rarely colourless, white or gray. Prehnite has a pearly to waxy or greasy texture and can be associated with Datolite, Calcite, Epidote or Apophyllite.
In Mali, numerous Prehnite deposits were found in the late 1980's, many of them in the vicinity of the Bandougou village, some 400 km west of Bamako. Most Prehnite from that area comes in nodular masses and spheres of yellowish green to bluish green. They are often associated with one to five centimeter prismatic dark green to black Epidote.