Hornblende

Hornblende, or Amphibole, a group of mineral silicates of magnesium and calcium, the former predominating, with occasionally iron, aluminium, sodium, or other metals. Hornblende, the black aluminous variety, occurs in syenite, syenitic granite, diorite, and some andesites and trachytes. Adinolite, a bright green form, occurs ill needles, fibres, and narrow crystals in hornblende-schists and amphibolites. Nephrite, another green form, forme- the hard tough substance known as jade (q.v.). Asbestos (q.v.) is a fibrous white variety.