Apophyllite is unique in that the name designates not a single mineral, but rather a certain class of minerals of similar chemical makeup that comprise a solid solution series. This class includes the members fluorapophyllite-(K), fluorapophyllite-(Na) and hydroxyapophyllite-(K). The name apophyllite is derived from the Greek word apophylliso, meaning "it flakes off", which indicates a reference to this class's tendency to flake apart when heated, due to water loss. These minerals typically appear as secondary minerals in vesicles in basalt or other volcanic rocks. Though apophyllites are relatively unfamiliar to the general public, they are fairly prevalent around the world, with specimens coming from some of the world's most well-known mineral localities. Such localities include: Jalgaon, India; the Harz Mountains of Germany, Mont Saint-Hilaire in Canada, and Kongsberg, Norway, with other locations in Scotland, Ireland, Brazil, Japan, and throughout the United States. This excellent specimen makes a great addition to any earth science classroom for decoration, or for inclusion in a rock or mineral collection.
Color: Usually white, colorless; also blue, green, brown, yellow, pink, violet
Color of streak: White
Moh’s hardness: 4.5-5
Specific gravity: 2.3-2.4
Cleavage: Perfect on (001)
Crystal system: Prismatic, tabular, massive
Chemical composition: (K,Na)Ca4Si8O20(F,OH)·8H2O
Transparency: Transparent to translucent
Refractive index: 1.536
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