chromite is the most important ore of chromium from which it derives its name

8/17/2019 Chromite is the Most Important Ore of Chromium From Which It Derives Its Name

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Chromite is the most important ore of chromium from which itderives its name. Chromium is an important metal and has a widerange of industrial uses.

Chromite forms in deep ultra-mafic magmas and is one of the firstminerals to crystallize. It is because of this fact that chromite isfound in some concentrated ore bodies. While the magma is slowlycooling inside the Earth's crust, chromite crsytals are forming andbecause of their density, fall to the bottom and are concentratedthere.

lthough its primary origin is ultra-mafic roc!s such as peridotites,chromite is also found in metamorphic roc!s such as serpentites.Chromite, as is indicated by its early crystallization is resistant to

the altering affects of high temperatures and pressures. "hus it iscapable of going through the metamorphic processes unscathed,while other minerals around it are being alteredto serpentine, biotite and garnets. "his characteristic alsoe#plains chromites use as a refractory component in the bric!s andlinings of blast furnaces.

$sually magnesium is present in chromite substituting for the ironand in fact a solid solution series e#ists between chromite and the

much rarer mineral magnesiochromite. ll chromite specimens innature contain some magnesium, li!ewise all naturalmagnesiochromites contain some iron. %agnesiochromite is grayerin color and in strea! and has a slightly lower density than chromiteat a specific gravity of &. to &.&.

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Chromite, a mineral ore that is mined from crystallized magma, is used in theproduction of steel as a pigment and as a catalyst in many chemical reactions. It is also

an important component of the leather tanning process. Chromite is also used to

anodize aluminum for use in jet engines.

Spinel Group. It apparently forms a complete solid solution series with many other members

of the group, eg. in the Chromite-Hercynite Series,Chromite-Spinel Series, Chromite-

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Magnetite Series and the Chromite-Magnesiochromite Series. It is the iron analogue

of Zincochromite, Cochromite,Manganochromite and Magnesiochromite and the Cr analogue

of Hercynite, Coulsonite and Magnetite

It usually contains Mg, ferric iron !e"III#$, %l and often &i. '!errichromite', i.e. !e"III#

substitutions for %l and Cr, usually in grain rims, may gi(e high total !e contents and a false

chromite identi)cation. *f course, the de)nition re+uires dominant !e"II#Mg and Cr!e"III#.

"e.g. photo I /01231#.

'Chromite' is commonly used for any Cr-rich mineral of the spinel group, particularly for the

chromite-magnesiochromite series, and much of the mineral referred to as 'chromite' in

geological and petrological papers and mining statistics is usually Magnesiochromite. &he !e-

dominant species - Chromite itself - can be !*45, although uncommonly, in many

'chromite' deposits, chromitite "roc6 name#, and other 'chromite'-bearing occurrences

connected with hyperbasic roc6s. %s a rule of thumb, a member of the chromite-

magnesiochromite series is twice as li6ely to be a magnesiochromite instead of a chromite.

'Chromites' associated with oli(ine or serpentines, which are Mg-rich roc6s, fre+uently ha(e

Mg-rich associated minerals. &rue chromite is common as inclusions in iamonds from6imberlites "South %frica and 7a6utia#. Members of the spinel group may be enriched Cr and

8 in marbles "Slyudyan6a#, massi(e sulphide ores "*uto6umpu# and also in some types of

meteorites. In any case, 'chromite' always needs %5%97&IC%9 C*5!I:M%&I*5. 5ote

Chromite, that is near end-member, has a higher speci)c gra(ity than near end-member

magnesiochromite.

Classifcation o Chromite

IMA status:

8alid - )rst described prior to 03/3 "pre-IM%# - 'Grandfathered'

Strunz 8th ed.:

1;-?=

Nickel-Strunz 10th !endin"# ed.:

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.01.0?

*Bides and HydroBides

01 *Bides of Cr

chromite is the most important ore of chromium from which it derives its name

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