pyroxene

[Pref. pyro-, and Gr. xenos =a stranger.] Min.: A name used for a group of minerals of very variable composition and origin, but all of amphiboles) to the same chemical type, under the which are referable (like the analogous group of general formula ROSIO2, where R may represent lime, magnesia, the protoxides of iron and manganese, and sometimes soda, potash, and oxide of C6H4(NO)2 HOKO), N. Obtained by diluting with water a solution of pyrotartranil in strong nitric acid. It crystallizes from boiling alcohol in groups of crystals; is nearly insoluble in water, easily soluble in alcohol and ether, and melts at 155°. Boiled with aqueous ammonia it it is converted ammonium.