Magnesiochromite

MgCr₂O₄

Hardness: 5.5
Streak: Dark gray
Spec. Gravity: 4.2
System: Isometric

About

Magnesiochromite is very similar to Chromite, and is often mistaken for it. Due to their similarity, it is very difficult to visually distinguish these two minerals. Magnesiochromite is the magnesium-dominating form in a series with Chromite, whereas Chromite is iron-dominating.

Crystal Forms & Aggregates

Crystals, which are octahedral, are very rare. Usually grainy, massive, and as rounded embedded masses.

Striking Features

Streak and hardness

Environment

In Serpentine deposits, as well as in ultrabasic igneous rocks. May also be in placer deposits.

Noteworthy Localities

Magnesiochromite does not have well defined localities, as it occurs scattered in chrome deposits together with Chromite. The type locality for this mineral is Schwarzenberg, in the Erzgebirge, Saxony, Germany. Other occurrences are the Saranovskoye Mine, Sarany, Ural Mountains, Russia; Soldiers Delight, Owings Mill, Baltimore Co., Maryland; and the Cedar Mountain Ridge Chromite deposit, near Livermore, Alameda Co., California.

Common Mineral Associations

Chromite, Serpentine, Clinochlore, Magnetite, Uvarovite

Distinguishing Similar Minerals

Chromite - Has a brownish streak, is slightly attracted to magnetic fields.

Photos

Crystal forms

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Octahedral

Magnesiochromite

Abouti

Crystal Forms & Aggregatesi

Striking Featuresi

Environmenti

Noteworthy Localitiesi

Common Mineral Associationsi

Distinguishing Similar Mineralsi