Humite Mineral Data

General Humite Information

Chemical Formula:

(Mg,Fe++)7(SiO4)3(F,OH)2

Composition:

Molecular Weight = 538.58 gm

Magnesium 23.69 % Mg 39.29 % MgO

Iron 18.15 % Fe 23.34 % FeO

Silicon 15.64 % Si 33.47 % SiO₂

Hydrogen 0.09 % H 0.84 % H₂O

Oxygen 37.13 % O

Fluorine 5.29 % F 5.29 % F

- % F -2.23 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg_5.25Fe²⁺_1.75(SiO₄)₃F_1.5(OH)_0.5

Environment:

Commonly interlayered with clinohumite.

IMA Status:

Valid Species (Pre-IMA) 1813

Locality:

Mte. Somma, Vesuvius, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for Abraham Hume (1749-1838), English connoisseur and collector of works of art, precious stones and minerals.

Name Pronunciation:

Humite

Synonym:

ICSD 34847

PDF 12-755

Humite Image

Images:

Humite

Comments: Striated, brown, tabular crystals of humite.
Location: Monte Somma (Vesuvius), Campania, Italy. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Humite Crystallography

Axial Ratios:

a:b:c =0.4943:1:0.2285

Cell Dimensions:

a = 10.243, b = 20.72, c = 4.735, Z = 4; V = 1,004.93 Den(Calc)= 3.56

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P nma

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.256(1), 1.479(0.7), 2.438(0.7),

Crystal Structure:

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Ribbe P H , Gibbs G V , American Mineralogist , 56 (1971) p.1155-1173, Crystal structures of the humite minerals: III. Mg/Fe ordering in humite and its, relation to other ferromagnesian silicates

Physical Properties of Humite

Cleavage:

{001} Poor

Color:

Brown, Yellow, White, Dark orange.

Density:

3.1 - 3.2, Average = 3.15

Diaphaneity:

Transparent to translucent

Fracture:

Conchoidal - Uneven - Uneven fracture producing small, conchoidal fragments.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Humite

Gladstone-Dale:

CI meas= -0.028 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.09 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1796,KPDmeas= 0.203,KC= 0.1974
Ncalc = 1.61 - 1.7

Optical Data:

Biaxial (+), a=1.607-1.643, b=1.619-1.653, g=1.639-1.675, bire=0.0320, 2V(Calc)=70-78, 2V(Meas)=68-81. Dispersion weak, r > v.

Pleochroism (x):

pale golden yellow or deep golden yellow.

Pleochroism (y):

pale yellow or colorless.

Pleochroism (z):

golden yellow or pale yellow.

Calculated Properties of Humite

Electron Density:

Bulk Density (Electron Density)=3.09 gm/cc
note: Specific Gravity of Humite =3.15 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Humite= 6.53 barns/electron
U=PE_Humite x rElectron Density= 20.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Humite is Not Radioactive

Humite Classification

Dana Class:

52.03.02c.01 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.03)with cations in [6] coordination only

(52.03.02c)Humite group (Humite series)

52.03.02c.01 Humite (Mg,Fe)7(SiO4)3(F,OH)2 P nma 2/m 2/m 2/m

52.03.02c.02 Leucophoenicite Mn7(SiO4)3(OH)2 P 2₁/a 2/m

52.03.02c.03 Manganhumite (Mn,Mg)7(SiO4)3(OH)2 Pbnm 2/m 2/m 2/m

52.03.02c.04 Chegemite! Ca7(SiO4)3(OH)2 Pbnm 2/m 2/m 2/m

Strunz Class:

09.AF.50 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.50 Manganhumite (Mn,Mg)7(SiO4)3(OH)2 Pbnm 2/m 2/m 2/m

09.AF.50 Humite (Mg,Fe)7(SiO4)3(F,OH)2 P nma 2/m 2/m 2/m

09.AF.50 Chegemite! Ca7(SiO4)3(OH)2 Pbnm 2/m 2/m 2/m

Other Humite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Ask about Humite here :
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Print or Cut-and-Paste your Humite Specimen Label here :

Humite

(Mg,Fe++)7(SiO4)3(F,OH)2
Dana No: 52.03.02c.01 Strunz No: 09.AF.50
Locality:

Notes: