Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Lepidocrocite

This page is currently not sponsored. Click here to sponsor this page.
Formula:
γ-Fe3+O(OH)
System:
Orthorhombic
Colour:
Deep red, red-brown
Lustre:
Sub-Metallic
Hardness:
5
Name:
From the Greek λεπίς, scale, and κροκη, thread, in allusion to the occasional palmate or plumose aggregates.
Dimorphous with Goethite.

May be a component of limonite.

The red inclusions in many quartz crystals, often labelled by sellers as "lepidocrocite", are in fact normally hematite. We are unaware of any analytically confirmed red translucent scaly lepidocrocite as inclusions in quartz crystals. Likewise, colourfully iridescent mammillary "turgite" crusts are sometimes sold as "lepidocrocite" but are usually goethite.


Classification of Lepidocrocite

Approved, 'Grandfathered' (first described prior to 1959)
4.FE.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
6.1.2.2

6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
7.20.8

7 : Oxides and Hydroxides
20 : Oxides of Fe

Type Occurrence of Lepidocrocite

Physical Properties of Lepidocrocite

Sub-Metallic
Diaphaneity (Transparency):
Transparent
Colour:
Deep red, red-brown
Streak:
Orange
Hardness (Mohs):
5
Tenacity:
Brittle
Cleavage:
Perfect
{010}; {100} less perfect; {001} good.
Density:
4.05 - 4.13 g/cm3 (Measured)    3.96 g/cm3 (Calculated)

Crystallography of Lepidocrocite

Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Cmc21
Cell Parameters:
a = 3.07Å, b = 12.54Å, c = 3.88Å
Ratio:
a:b:c = 0.245 : 1 : 0.309
Unit Cell Volume:
V 149.37 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Flattened scales {010} and slightly elongated [100]. {010} sometimes striated [100]. Single crystals attached by an edge to matrix; aggregated into palmate or plumose groups. Loose rosettes; massive, bladed to fibrous or micaceous. Fibrous varieties elongated [100].
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
6.26 (100)
3.29 (90)
2.47 (80)
1.937 (70)
1.732 (40)
1.524 (40)
1.075 (40)

Optical Data of Lepidocrocite

Type:
Biaxial (-)
RI values:
nα = 1.940 nβ = 2.200 nγ = 2.510
2V:
Measured: 83° , Calculated: 84°
Max Birefringence:
δ = 0.570
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Type:
Anisotropic
Anisotropism:
Strong
Dispersion:
relatively weak
Colour in reflected light:
Gray-white
Pleochroism:
Strong
Comments:
X = b = clear yellow
Y = c = dark red-orange
Z = a = darker red-orange

Chemical Properties of Lepidocrocite

Formula:
γ-Fe3+O(OH)
All elements listed in formula:
Common Impurities:
Mn

Relationship of Lepidocrocite to other Species

4.FE.05Amakinite(Fe2+,Mg)(OH)2
4.FE.05BruciteMg(OH)2
4.FE.05PortlanditeCa(OH)2
4.FE.05PyrochroiteMn(OH)2
4.FE.05TheophrastiteNi(OH)2
4.FE.10BayeriteAl(OH)3
4.FE.10DoyleiteAl(OH)3
4.FE.10GibbsiteAl(OH)3
4.FE.10NordstranditeAl(OH)3
4.FE.15BöhmiteAlO(OH)
4.FE.20GrimaldiiteCrO(OH)
4.FE.20HeterogeniteCo3+O(OH)
4.FE.25FeitknechtiteMn3+O(OH)
4.FE.25Lithiophorite(Al,Li)MnO2(OH)2
4.FE.30QuenselitePbMnO2(OH)
4.FE.35FerrihydriteFe103+O14(OH)2
4.FE.40FeroxyhyteFe3+O(OH)
4.FE.40Vernadite(Mn4+,Fe3+,Ca,Na)(O,OH)2 · nH2O
4.FE.45QuetzalcoatliteZn6Cu3(TeO6)2(OH)6 · AgxPbyClx+2y
7.20.1WüstiteFeO
7.20.2MagnetiteFe2+Fe23+O4
7.20.3MaghemiteFe23+O3
7.20.4HematiteFe2O3
7.20.5Goethiteα-Fe3+O(OH)
7.20.6Akaganeite(Fe3+,Ni2+)8(OH,O)16Cl1.25 · nH2O
7.20.7FeroxyhyteFe3+O(OH)
7.20.9FerrihydriteFe103+O14(OH)2
7.20.10Amakinite(Fe2+,Mg)(OH)2
7.20.11MagnesioferriteMgFe23+O4
7.20.12MuskoxiteMg7Fe4O13 · 10H2O
7.20.13SrebrodolskiteCa2Fe23+O5
7.20.14HercyniteFe2+Al2O4
7.20.15BrownmilleriteCa2(Al,Fe3+)2O5

Other Names for Lepidocrocite

Other Information

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

References for Lepidocrocite

Reference List:
Posnjak, E., Merwin, H.E. (1919) The hydrated ferric oxides. American Journal of Science: 47: 311-348.

Palache, C., Berman, H., Frondel, C. (1944) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 642-645.

(1978) Acta Chemica Scandinavica: A: 87.

Internet Links for Lepidocrocite

mindat.org URL:
http://www.mindat.org/min-2379.html
Please feel free to link to this page.

Localities for Lepidocrocite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2016, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: December 8, 2016 04:06:52 Page generated: November 29, 2016 04:12:45
Go to top of page