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Mineral group · Silicate

Glauconite

(K,Na)(Fe,Al,Mg)₂(Si,Al)₄O₁₀(OH)₂

Green marine clay mica of 'greensand' deposits.

Hardness2
Crystal systemMonoclinic
ClassSilicate
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Glauconite specimen

Glauconite from Bellegarde, Ain, France — Photo: Kritzolina · CC0

Glauconite

The green iron-potassium mica that gives 'greensand' its color — a friable mineral of marine sediments.

Intro adapted from Wikipedia (CC BY-SA).

Glauconite is a mineral group, with the chemical formula (K,Na)(Fe,Al,Mg)₂(Si,Al)₄O₁₀(OH)₂.

It crystallizes in the monoclinic crystal system.

Key properties: Mohs hardness 2; specific gravity 2.675; typically green; refractive index 1.618; optically biaxial.

Collections: Everyday Minerals.

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 G minerals or help write this entry.