About
Hornblende is major constituent of the earth and is extremely common. It forms in a host of different mineral environments, and is often a major constituent of the rock type it forms in. Hornblende is a rock-forming mineral, and it even constitutes its own rock type known as Horneblendite, a dark rock formed mostly from Hornblende.
Hornblende is named after the German term horn, referring to its color, and blenden, meaning "deceiver", alluding to its habit of being confused with ore metals due to its dark color and luster. Its typical dark color and opacity are usually caused by iron in its structure.
Crystal Forms & Aggregates
Striking Features
Environment
Uses
Noteworthy Localities
Lustrous, well-formed crystals, mostly as microcrystals, come from the Italian volcanoes at Monte Somma, Vesuivius; and at the Montenero Quarry, Latera, Lazio Province. Exceptional crystals in relatively large prismatic crystals have come from Studsdalen, near Kragerø, Telemark, Norway. Other Norwegian localities include Arendal, Langesundfjord; and several localities in Risør, Aust-Agder. Dark green Hornblende was found in Malmberget, Gällivare, Sweden; and doubly terminated floater crystals have come from Žim (Schima), Teplice, Bohemia, in the Czech Republic.
In the U.S., shiny Hornblende crystal plates have come from the iron mines in the Jersey Highlands in Bergen, Passaic, and Sussex Counties, New Jersey; and across the state border in the Ramapo Mountains and Hudson Highlands Region in Rockland, Orange, and Putnam Counties. Good Hornblende crystals have come from upstate New York regions in St. Lawrence Co. at Edwards, Pierrepont, Gouverneur, and Russel. In Canada, lustrous, well-formed stubby crystals come from Bancroft, Ontario; and at the Bear Lake Diggings in Gooderham, Haliburton Co., Ontario.
Common Mineral Associations
Distinguishing Similar Minerals
Schorl - Lacks the good cleavage, is heavily striated, and different crystal form.
Actinolite and Diopside - Lighter in color.