Heulandite, which is composed of Hydrous Calcium and Aluminum Silicate, is a tectosilicate that is named after a famous British mineral collector called John Henry Heuland. It is a member of the zeolite group, and is well known for its intricate crystal systems which can have either a vitreous or a pearly luster. They can be a variety of colors, from colorless to white, gray, green, pink, yellow, red, brown or black, dependent on the levels of metallic impurities. Typically, these are made up of strontium, potassium, magnesium, and barium. Heulandite is found in many parts of the world, often in association with rare minerals such as apophyllite, prehnite, and tourmaline. It has a vitreous to pearly luster and a white streak, with a specific gravity or 2.1 - 2.3.
(Ca,Na)2,3Al3(Al,Si)2Si13O36-12H2O |
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