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Mineral group · Silicate

Hornblende

Ca₂(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH)₂

The commonest amphibole — now split into many -hornblende species.

Hardness5–6
Crystal systemMonoclinic
ClassSilicate
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Hornblende specimen

This andesite is an extrusive igneous rock with black hornblende crystals in a light-gray groundmass. The fine grained matrix is composed of plagioclase micro-c — Photo: Twyla Baker · CC0

Hornblende

The field name for the dark amphiboles — not a single species but a complex inosilicate series ubiquitous in igneous and metamorphic rocks.

Intro adapted from Wikipedia (CC BY-SA).

Hornblende is a mineral group, with the chemical formula Ca₂(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH)₂.

It crystallizes in the monoclinic crystal system.

Key properties: Mohs hardness 5–6; typically black or green.

Collections: Everyday Minerals, Collector Favorites.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet. Browse more H minerals or help write this entry.