Augit

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Augit is a very common mineral from the mineral class of “silicates and germanates”. As a clinopyroxene, it crystallizes in the monoclinic crystal system with the chemical composition (Ca,Mg,Fe)2Si2O6 and develops short to long, prismatic crystals, but also granular mineral aggregates of green, brown or black color in the case of grey-green line color. Very rarely colorless augite (Leukaugit) are also found.

With a Mohs hardness of 5 to 6, Augit belongs to the medium hard minerals and can be scratched similar to the reference mineral Apatite (hardness 5) with a knife or like the reference mineral Orthoklas with a steel file.

Etymology and History
Augit was first described in 1792 by the German mineralogist Abraham Gottlob Werner and named after him.

Classification
The structural classification published in 1989 by the International Mineralogical Association (IMA) classifies the augite together with burnettit, Davisit, diopside, Essenit, Grossmanit, Hedenbergit, Johannsenit, Kushiroit, Petedunnit and Tissintit to the calcium pyroxenes (Ca pyroxenes) in the pyroxene group.

In the obsolete 8. Edition of the mineral systematics according to Strunz, the Augit belonged to the mineral class of “silicates and germanates” and there to the general division of the “chain and belt silicates (inosilicates)”, where he formed the “Augit series” with the system no. VIII/D.01d and the other members Aegirin-Augit, Fassait (now discredited as a variety) and Omphacite within the pyroxene family belonging to the pyroxene family.

In the Lapis Mineral List according to Stefan Weiss, which, out of consideration for private collectors and institutional collections, still follows this old form of Karl Hugo Strunz's systematics, the mineral received the system and mineral no. VIII/F.01-90. In the “Lapis Systematic”, this also corresponds to the class “chain and belt silicates”, where Augit together with Aegirin, Aegirin-Augit, Augit, Davisit, Diopside, Esseneit, Grossmanit, Hedenbergit, Jadeit, Jervisit, Johannsenit, Kanoit, Clino-Statit, Clinoferrosilite, Cosmochlor, Kushiroit, Namansilit, Natalyit, Omphacit, Petedunnit, Pigeonite, Spodumen and Tissintit forms the group of “Clinopyroxenes” (as of 2018).

Also valid since 2001 and last updated by the International Mineralogical Association (IMA) in 2009. The edition of Strunz’s Mineral Systematics places the Augit in the department of “chain and belt silicates (inosilicates)”. However, this is further subdivided according to the structure of the chain or ribbons and the relatedness of some minerals, so that the mineral is correspondingly subdivided into the subdivision “chain and ribbon silicates with 2-periodic single chain Si2O6”; Pyroxene family" can be found, where together with Davisit, Diopsid, Esseneit, Hedenbergit, Johannsenit, Kushiroit and Petedunnit it forms the "Ca-Clinopyroxene, Diopsid group" with system no. 9.DA.15.

The systematics of