Johannsenite Mineral Data

Johannsenite Mineral Data +

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General Johannsenite Information

Chemical Formula:

CaMnSi2O6

Composition:

Molecular Weight = 247.18 gm

Calcium 16.21 % Ca 22.69 % CaO

Manganese 22.23 % Mn 28.70 % MnO

Silicon 22.72 % Si 48.62 % SiO₂

Oxygen 38.84 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaMn²⁺(Si₂O₆)

Environment:

Contact metasomatic rocks.

IMA Status:

Valid Species (Pre-IMA) 1932

Locality:

Empire Zinc Company mine near Hanover, Grant County, New Mexico. Link to MinDat.org Location Data.

Name Origin:

Named after Prof. Albert Johannsen of the University of Chicago.

Synonym:

ICSD 16906

PDF 38-413

Johannsenite Image

Images:

Johannsenite

Comments: Mass of prismatic bluish green colored johannsenite crystals.
Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 7.2 x 4 cm.
© John Veevaert

Images:

Johannsenite

Comments: Rounded glassy prismatic crystals of dark violet brown johannsenite to 1.4 cm. Long.
Location: Consols Mine, Broken Hill, NSW, Australia. Scale: 1.5x1.5x1 cm.
© Richard Dale / Dale Minerals

Johannsenite Crystallography

Axial Ratios:

a:b:c =1.0897:1:0.578

Cell Dimensions:

a = 9.978, b = 9.156, c = 5.293, Z = 4; beta = 105.48° V = 466.02 Den(Calc)= 3.52

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c

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

By Intensity(I/I_o): 3.048(1), 2.573(0.43), 3.025(0.43),

Crystal Structure:

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Freed R L , Peacor D R , American Mineralogist , 52 (1967) p.709-720, Refinement of the crystal structure of johannsenite

Physical Properties of Johannsenite

Cleavage:

[110] Good

Color:

Brown, Brownish black, Greenish, Gray, Gray green.

Density:

3.56

Diaphaniety:

Translucent to opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

6 - Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

greenish gray

Optical Properties of Johannsenite

Gladstone-Dale:

CI meas= 0.011 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2053,KPDmeas= 0.2029,KC= 0.2053

Optical Data:

Biaxial (+), a=1.703-1.716, b=1.711-1.728, g=1.732-1.745, bire=0.0290, 2V(Calc)=64-82, 2V(Meas)=68-70.

Calculated Properties of Johannsenite

Electron Density:

r_electron=3.45 gm/cc
note: r_Johannsenite=3.52 gm/cc.

Fermion Index

Fermion Index = 0.01101
Boson Index = 0.98899

Photoelectric:

PE_Johannsenite= 8.51 barns/electron
U=PE_Johannsenite x r_electron= 29.34 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Johannsenite is Not Radioactive

Johannsenite Classification

Dana Class:

65.1.3a.4 (65)Inosilicate Single-Width Unbranched Chains, W=1

(65.1)with chains P=2

(65.1.3a)C2/c clinopyroxenes (Ca clinopyroxenes)

65.1.3a.1 Diopside CaMgSi2O6 C 2/c 2/m

65.1.3a.2 Hedenbergite CaFeSi2O6 C 2/c 2/m

65.1.3a.3 Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 C 2/c 2/m

65.1.3a.4 Johannsenite CaMnSi2O6 C 2/c 2/m

65.1.3a.5 Petedunnite Ca(Zn,Mn,Fe,Mg)Si2O6 C 2/c 2/m

65.1.3a.6 Esseneite CaFeAlSiO6 C 2/c 2/m

Strunz Class:

VIII/F.01-70 VIII - Silicates

VIII/F - Inosilicates (chain and band) double chains [Si2O6]4-

VIII/F.01 - Pyroxene group, Clinopyroxene

VIII/F.01-10 Clinoenstatite Mg2Si2O6 P 2₁/c 2/m

VIII/F.01-20 Clinoferrosilite (Fe,Mg)2Si2O6 P 2₁/c 2/m

VIII/F.01-30 Kanoite (Mn,Mg)2Si2O6 P 2₁/c 2/m

VIII/F.01-40 Pigeonite (Mg,Fe,Ca)(Mg,Fe)Si2O6 P 2₁/c 2/m

VIII/F.01-50 Diopside CaMgSi2O6 C 2/c 2/m

VIII/F.01-60 Hedenbergite CaFeSi2O6 C 2/c 2/m

VIII/F.01-70 Johannsenite CaMnSi2O6 C 2/c 2/m

VIII/F.01-80 Petedunnite Ca(Zn,Mn,Fe,Mg)Si2O6 C 2/c 2/m

VIII/F.01-90 Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 C 2/c 2/m

VIII/F.01-100 Omphacite (Ca,Na)(Mg,Fe,Al)Si2O6 P 2/n 2/m

VIII/F.01-110 Esseneite CaFeAlSiO6 C 2/c 2/m

VIII/F.01-120 Spodumene LiAlSi2O6 C 2/c 2/m

VIII/F.01-130 Jadeite Na(Al,Fe)Si2O6 C 2/c 2/m

VIII/F.01-140 Aegirine NaFeSi2O6 C 2/c 2/m

VIII/F.01-145 Namansilite NaMn(Si2O6) C 2/c 2/m

VIII/F.01-150 Jervisite (Na,Ca,Fe)(Sc,Mg,Fe)Si2O6 C 2/c 2/m

VIII/F.01-160 Natalyite Na(V,Cr)Si2O6 C 2/c 2/m

VIII/F.01-170 Kosmochlor NaCrSi2O6 C 2/c 2/m

Other Johannsenite Information

References:

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

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Johannsenite

CaMnSi2O6
Dana No: 65.1.3a.4 Strunz No: VIII/F.01-70
Locality:

Notes: