Gahnite
A species of Minerals, Also known as Automolite, Dysluite, Gahnite (of von Moll), Zinc Spinel Scientific name : Gahnite RockType : Minerals
Gahnite, A species of Minerals
Also known as:
Automolite, Dysluite, Gahnite (of von Moll), Zinc Spinel
Scientific name: Gahnite
RockType: Minerals
Content
Description General Info
, used under PUBLIC-DOMAIN /Cropped and compressed from original 
Description
Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill, Australia. Other occurrences include Falun, Sweden where it is found in pegmatites and skarns, Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine; and Franklin, New Jersey in the United States. It was first described in 1807 for an occurrence in the Falu mine, Falun, Dalarna, Sweden, and named after the Swedish chemist, Johan Gottlieb Gahn (1745–1818), the discoverer of the element manganese. It is sometimes called zinc spinel. 
Physical Properties
Colors
Dark blue-green, yellow, brown, black
Refractive Index
1.790-1.818
Optical Character
Isotropic
Chemical Properties
Formula
ZnAl2O4
Elements listed
Al, O, Zn
Common Impurities
Fe,Mg
General Info
How to Select
High-quality gahnite is often small, making larger sizes uniquely valuable. Faceted gems are collectible due to their blue color and rarity. As a crystal specimen, the gahnite produces octahedron crystals that show twinning, something for which this mineral is known. When in doubt, request a certificate of authenticity, as specimens can be chemically analyzed.
, used under PUBLIC-DOMAIN /Cropped and compressed from original 
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