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.

Name Pronunciation:

Johannsenite + Pronunciation

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

Diaphaneity:

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
Ncalc = 1.72 - 1.73

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:

Bulk Density (Electron Density)=3.45 gm/cc
note: Specific Gravity of Johannsenite =3.52 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Johannsenite= 8.51 barns/electron
U=PE_Johannsenite x rElectron Density= 29.34 barns/cc.

Radioactivity:

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

Johannsenite Classification

Dana Class:

65.01.03a.04 (65)Inosilicate Single-Width Unbranched Chains, W=1

(65.01)with chains P=2

(65.01.03a)C2/c clinopyroxenes (Ca clinopyroxenes)

65.01.03a.01 Diopside CaMgSi2O6 C 2/c 2/m

65.01.03a.02 Hedenbergite CaFeSi2O6 C 2/c 2/m

65.01.03a.03 Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 C 2/c 2/m

65.01.03a.04 Johannsenite CaMnSi2O6 C 2/c 2/m

65.01.03a.05 Petedunnite Ca(Zn,Mn,Fe,Mg)Si2O6 C 2/c 2/m

65.01.03a.06 Esseneite CaFeAlSiO6 C 2/c 2/m

65.01.03a.07 Davisite! Ca(Sc,Ti,Mg,Ti)AlSiO6 C 2/c 2/m

Strunz Class:

09.DA.15 09 - SILICATES (Germanates)

09.D - Inosilicates* Structural terminology according to Liebau (1985)

09.DA -Inosilicates with 2-periodic single chains, Si2O6; pyroxene family

09.DA.15 Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 C 2/c 2/m

09.DA.15 Esseneite CaFeAlSiO6 C 2/c 2/m

09.DA.15 Diopside CaMgSi2O6 C 2/c 2/m

09.DA.15 Johannsenite CaMnSi2O6 C 2/c 2/m

09.DA.15 Hedenbergite CaFeSi2O6 C 2/c 2/m

09.DA.15 Petedunnite Ca(Zn,Mn,Fe,Mg)Si2O6 C 2/c 2/m

09.DA.15 Davisite! Ca(Sc,Ti,Mg,Ti)AlSiO6 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)

See Also:

Links to other databases for Johannsenite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Dunn)
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineral and Gemstone Kingdom
13 - Mineralienatlas (Deutsch)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - WWW-MINCRYST

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Print or Cut-and-Paste your Johannsenite Specimen Label here :

Johannsenite

CaMnSi2O6
Dana No: 65.01.03a.04 Strunz No: 09.DA.15
Locality:

Notes: