Montgomeryite Mineral Data
General Montgomeryite Information
Chemical Formula:
Ca4MgAl4(PO4)6(OH)4•12(H2O)
Composition:
Molecular Weight = 1,146.58 gm
Calcium 13.98 % Ca 19.56 % CaO
Magnesium 2.12 % Mg 3.52 % MgO
Aluminum 9.41 % Al 17.79 % Al2 O3
Phosphorus 16.21 % P 37.14 % P2 O5
Hydrogen 2.46 % H 22.00 % H2 O
Oxygen 55.82 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca4 MgAl4 (PO4 )6 (OH)4 •12(H2 O)
Environment:
Forms a series with kingsmountainite.
IMA Status:
Valid Species (Pre-IMA) 1940
Locality:
Little Green Monster mine, Clay Canyon, Fairfield, Utah County, Utah, USA. Link to MinDat.org Location Data.
Name Origin:
Named for Arthur Mongomery (1909-), mineralogist, teacher, collector, and founder of the Friends of Mineralogy.
Name Pronunciation:
Montgomeryite + Pronunciation
Synonym:
ICSD 64849
PDF 28-225
Montgomeryite Image
Images:
Montgomeryite
Comments: Matrix specimen covered with sprays to 0.5 cm of salmon colored montgomeryite crystals.
Location: Tip Top Mine, Custer County, South Dakota, USA.
Scale: 13 x 8 cm.
© John Veevaert
Images:
Images:
Tiptopite Englishite Montgomeryite
Comments: Red montgomeryite lath-like crystals to 1mm in 2mm rosettes associated with clear, acicular sprays of tiptopite to 0.75mm and white cottonball-like crystals of englishite to 0.2mm.
Location: Tip Top mine, Custer Co., South Dakota, USA.
Scale: Picture size 5 mm.
© Tom Loomis / Dakota Matrix
Montgomeryite Crystallography
Axial Ratios:
a:b:c =0.4155:1:0.2588
Cell Dimensions:
a = 10.023, b = 24.121, c = 6.243, Z = 2; beta = 91.55° V = 1,508.79 Den(Calc)= 2.52
Crystal System:
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/c
X Ray Diffraction:
By Intensity(I/Io ): 5.115(1), 12.1(0.56), 2.617(0.32),
Physical Properties of Montgomeryite
Cleavage:
{010} Perfect, {100} Indistinct
Color:
Colorless, Yellowish, White, Green, Red.
Density:
2.46 - 2.53, Average = 2.49
Diaphaneity:
Transparent to Translucent
Hardness:
4 - Fluorite
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Montgomeryite
Gladstone-Dale:
CI meas = -0.016 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = -0.006 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2291,KPDmeas = 0.2314,KC = 0.2277 Ncalc = 1.56 - 1.58
Optical Data:
Biaxial (-), a=1.572, b=1.578, g=1.582, bire=0.0100, 2V(Calc)=78, 2V(Meas)=75.
Calculated Properties of Montgomeryite
Electron Density:
Bulk Density (Electron Density)=2.56 gm/cc note: Specific Gravity of Montgomeryite =2.52 gm/cc.
Fermion Index:
Fermion Index = 0.0025801362 Boson Index = 0.9974198638
Photoelectric:
PEMontgomeryite = 2.83 barns/electronU=PEMontgomeryite x r Electron Density= 7.25 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Montgomeryite is Not Radioactive
Montgomeryite Classification
Dana Class:
42.11.08.01 (42) Hydrated Phosphates, etc., Containing Hydroxyl or Halogen
(42.11) where (AB)4 (XO4)3 Zq � x(H2O)
(42.11.08) Montgomeryite group
42.11.08.01 Montgomeryite Ca4MgAl4(PO4)6(OH)4•12(H2O) C 2/c 2/m
42.11.08.02 Kingsmountite (Ca,Mn)4(Fe,Mn)Al4(PO4)6(OH)4•12(H2O) C 2 2
42.11.08.03 Calcioferrite Ca4Fe(Fe,Al)4(PO4)6(OH)4•12(H2O) C 2 2
42.11.08.04 Zodacite Ca4MnFe4(PO4)6(OH)4•12(H2O) C 2/c,Cc Mono
42.11.08.05 Angastonite ! CaMgAl2(PO4)2(OH)4?7H2O P1 1
Strunz Class:
08.DH.25 08 - PHOSPHATES, ARSENATES, VANADATES
08.D - Phosphates, etc
08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1
08.DH.25 Calcioferrite Ca4Fe(Fe,Al)4(PO4)6(OH)4•12(H2O) C 2 2
08.DH.25 Kingsmountite (Ca,Mn)4(Fe,Mn)Al4(PO4)6(OH)4•12(H2O) C 2 2
08.DH.25 Montgomeryite Ca4MgAl4(PO4)6(OH)4•12(H2O) C 2/c 2/m
08.DH.25 Zodacite Ca4MnFe4(PO4)6(OH)4•12(H2O) C 2/c,Cc Mono
Other Montgomeryite Information
References:
NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Montgomeryite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST
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Print or Cut-and-Paste your Montgomeryite Specimen Label here :
Montgomeryite
Ca4MgAl4(PO4)6(OH)4•12(H2O)
Dana No: 42.11.08.01 Strunz No: 08.DH.25
Locality:
Notes:
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