Limonite

Christandl quarry, Peunt, Naintschgraben, Anger, Weiz, Styria, Austria
© ReMi

Show Limonite Photos (193)

Formula:

FeO(OH)·nH

Colour:

Light brown to brown, ...

Hardness:

4 - 5½

Name:

From the greek for meadow, from occurrences in bogs.

Currently used for unidentified massive hydroxides and oxides of iron, with no visible crystals, and a yellow-brown streak. 'Limonite' is most commonly the mineral species Goethite, but can also consist of varying proportions of maghemite, hematite, lepidocrocite, hisingerite, pitticite, jarosite group species, etc.

Classification of Limonite

IMA status:

Not Approved

Explanation of status:

It is a generic term used for undifferentiated hydrated iron oxides - often hydrated goethite.

mindat.org URL:

http://www.mindat.org/min-2402.html
Please feel free to link to this page.

Occurrences of Limonite

Geological Setting:

A very common material in the oxidized zones of iron-bearing deposits, it is produced by the decomposition of many iron minerals, particularly pyrite, with water being retained in varying amounts.

Physical Properties of Limonite

Lustre:

Earthy

Diaphaneity (Transparency):

Opaque

Colour:

Light brown to brown, may be yellowish-brown

Streak:

Yellowish brown to red

Hardness (Mohs):

4 - 5½

Comment:

Massive may be very soft.

Density (measured):

2.7 - 4.3 g/cm³

Crystallography of Limonite

Morphology:

While "limonite" is amorphous, a number of minerals are noted for decomposing to it without losing their crystal shape - particularly pyrite crystals. Any "crystals" of "limonite" are actually pseudomorphs of other minerals which have decomposed in this fashion.

Chemical Properties of Limonite

Formula:

FeO(OH)·nH

Essential elements:

Fe, H, O

All elements listed in formula:

Fe, H, O

Analytical Data:

While a "generic" formula is often given as stated here, "limonite" is really quite variable in composition - both in its levels of hydration and hydroxylation and in its cationic content. There really is no formual for it...

Other Names for Limonite

Synonyms:

Other Languages:

Czech:	Limonit
Estonian:	Limoniit
French:	Limonite
German:	Limonit Berggelb Bohnerz Ferrohydrit Gelbeisenstein Glanzeisenstein Hydrosiderit Hyposiderit Perlimonit Toneisenerz Toneisenstein
Hebrew:	לימוניט
Japanese:	褐鉄鉱
Lithuanian:	Limonitas
Polish:	Limonit
Portuguese:	Limonite

Romanian:	Limonit
Russian:	Лимонит
Slovak:	Limonit
Spanish:	Limonita Ferrohydrita Globoso Hierro arcilloso Hydrosiderita Hyposiderita Palustre Perlimonita
Swedish:	Limonit Gul Jernmalm Myrmalm Sjömalm

Varieties:

Adlerstein	Alumolimonite	Auriferous Limonite	Avasite	Bean Ore
Chromiferous Limonite	Liminitogelite	Limnite	Stilpnosiderite

Other Information

Health Warning:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Limonite

Reference List:

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Seventh edition, Volume I: 685-686.