from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A mineral, a basic calcium, aluminium and iron aluminosilicate, which occurs in stalagtitic aggregates or curved crystals, Ca2Al2Si3O10(OH)2.
from the GNU version of the Collaborative International Dictionary of English
- n. A pale green mineral occurring in crystalline aggregates having a botryoidal or mammillary structure, and rarely in distinct crystals. It is a hydrous silicate of alumina and lime.
from The Century Dictionary and Cyclopedia
- A mineral, usually of a pale-green color and vitreous luster, commonly occurring in botryoidal or globular forms with crystalline surface.
Named in 1789 after Hendrik Von Prehn (1733-1785), Dutch colonial governor. This was the first mineral to be named after a person. (Wiktionary)