1) Monoclinic mineral 
Hectorite is a rare soft, greasy, white clay mineral with a chemical formula of Na0.3(Mg,Li)3Si4O10(OH)2. Hectorite was first described in 1941 and named for an occurrence in the United States near Hector (in San Bernardino County, California, 30 miles east of Barstow.) Hectorite occurs with bentonite as an alteration product of clinoptilolite fro...