Jahnsite-(CaMnMg) Mineral Data

Jahnsite-(CaMnMg) Mineral Data +

General Jahnsite-(CaMnMg) Information

Chemical Formula:

CaMnMg2Fe+++2(PO4)4(OH)2·8(H2O)

Composition:

Molecular Weight = 813.34 gm

Calcium 4.93 % Ca 6.89 % CaO

Magnesium 5.98 % Mg 9.91 % MgO

Manganese 6.75 % Mn 8.72 % MnO

Iron 13.73 % Fe 19.63 % Fe₂O₃

Phosphorus 15.23 % P 34.90 % P₂O₅

Hydrogen 2.23 % H 19.93 % H₂O

Oxygen 51.15 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaMn²⁺Mg₂Fe³⁺₂(PO₄)₄(OH)₂·8(H₂O)

IMA Status:

Approved IMA 1974

Locality:

Tip Top pegmatite, Custer, South Dakota, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Richard H. Jahns (1915-1983), mineralogist and pegmatite expert, Stanford University, Palo Alto, California, USA.

Synonym:

Jahnsite

Jahnsite-(CaMnMg) Image

Images:

Jahnsite-(CaMnMg)

Comments: Brown, striated, transparent crystals of jahnsite-(CaMnMg) on matrix.
Location: Tip Top mine, Custer, Custer County, South Dakota, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Jahnsite-(CaMnMg) Crystallography

Axial Ratios:

a:b:c =2.0924:1:1.3907

Cell Dimensions:

a = 14.94, b = 7.14, c = 9.93, Z = 2; beta = 110.68° V = 991.00 Den(Calc)= 2.73

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2/a

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

By Intensity(I/I_o): 9.27(1), 2.825(0.8), 4.91(0.6),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Moore P B , Araki T , American Mineralogist , 59 (1974) p.964-973, Jahnsite, CaMnMg2(H2O)8Fe2(OH)2[PO4]4: A novel stereoisomerism of, ligands about octahedral corner-chains

Physical Properties of Jahnsite-(CaMnMg)

Cleavage:

[001] Good

Color:

Brown, Purplish brown, Yellow, Yellow orange, Greenish yellow.

Density:

2.706 - 2.718, Average = 2.71

Diaphaniety:

Transparent to Translucent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Hardness:

4 - Fluorite

Luster:

Vitreous - Adamantine

Streak:

white

Optical Properties of Jahnsite-(CaMnMg)

Gladstone-Dale:

CI meas= 0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.019 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2403,KPDmeas= 0.2419,KC= 0.245

Optical Data:

Biaxial (+), a=1.64, b=1.658, g=1.67, bire=0.0300

Pleochroism (x):

pale purple.

Pleochroism (y):

deep purplish brown.

Pleochroism (z):

greenish yellow.

Calculated Properties of Jahnsite-(CaMnMg)

Electron Density:

r_electron=2.71 gm/cc
note: r_{Jahnsite-(CaMnMg)}=2.71 gm/cc.

Fermion Index

Fermion Index = 0.0092
Boson Index = 0.9908

Photoelectric:

PE_{Jahnsite-(CaMnMg)}= 7.19 barns/electron
U=PE_{Jahnsite-(CaMnMg)} x r_electron= 19.50 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Jahnsite-(CaMnMg) is Not Radioactive

Jahnsite-(CaMnMg) Classification

Dana Class:

42.11.2.1 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.11)where (AB)4 (XO4)3 Zq · x(H2O)

(42.11.2)Dana Group

42.11.2.1 Jahnsite-(CaMnMg) CaMnMg2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

42.11.2.2 Jahnsite-(CaMnFe) CaMnFe2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

42.11.2.3 Jahnsite-(CaMnMn) CaMnMn2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

42.11.2.4 Jahnsite-(MnMnMn)* MnMnMn2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

Strunz Class:

VII/D.29-50 VII - Phosphates, Arsenates and Vanadates

VII/D - Water-bearing phosphates with unfamiliar anions, cations of very big and medium size: Al, Mg and Ca, Na, K

VII/D.29 - Whiteite - Jahnsite group

VII/D.29-10 Whiteite-(CaFeMg) Ca(Fe,Mn)Mg2Al2(PO4)4(OH)2·8(H2O) P 2₁/a 2/m

VII/D.29-20 Whiteite-(CaMnMg) CaMnMg2Al2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-30 Whiteite-(MnFeMg) (Mn,Ca)(Fe,Mn)Mg2Al2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-40 Rittmannite MnMnFeAl2(OH)2(PO4)4·8(H2O) P 2/a 2/m

VII/D.29-50 Jahnsite-(CaMnMg) CaMnMg2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-60 Jahnsite-(CaMnFe) CaMnFe2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-70 Jahnsite-(CaMnMn) CaMnMn2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-75 Jahnsite-(MnMnMn)* MnMnMn2Fe2(PO4)4(OH)2·8(H2O) P 2/a 2/m

VII/D.29-80 Keckite Ca(Mn,Zn)2Fe3(PO4)4(OH)3·2(H2O) P 2₁/a 2/m

Other Jahnsite-(CaMnMg) Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Jahnsite-(CaMnMg) :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas 10 - WWW-MINCRYST

Search for Jahnsite-(CaMnMg) using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Jahnsite-(CaMnMg) :
AA Mineral Specimens
A-Rocks Auction
Adams Minerals
B and L Minerals
Dakota Matrix
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Minernet.it
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Jahnsite-(CaMnMg) Mineral Data :

Ask about Jahnsite-(CaMnMg) here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Jahnsite-(CaMnMg) Specimen Label here :

Jahnsite-(CaMnMg)

CaMnMg2Fe+++2(PO4)4(OH)2·8(H2O)
Dana No: 42.11.2.1 Strunz No: VII/D.29-50
Locality:

Notes: