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 % Al₂O₃

Phosphorus 16.21 % P 37.14 % P₂O₅

Hydrogen 2.46 % H 22.00 % H₂O

Oxygen 55.82 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₄MgAl₄(PO₄)₆(OH)₄•12(H₂O)

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:

Montgomeryite Tiptopite

Comments: Clear, acicular crystals of tiptopite with red montgomeryite.
Location: Tip Top mine, Custer, Custer County, South Dakota, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Montgomeryite Tiptopite Englishite

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

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

By Intensity(I/I_o): 5.115(1), 12.1(0.56), 2.617(0.32),

Crystal Structure:

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Moore P B , Araki T , American Mineralogist , 59 (1974) p.843-850, Montgomeryite, Ca4Mg(H2O)12[Al4(OH)4(PO4)6]:. Its crystal structure and, relation to Vauxite, Fe2(H2O)4[Al4(OH)4(H2O)4(PO4)4].4H2O

View Additional jPOWD Structure files for Montgomeryite
[1]

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:

PE_{Montgomeryite}= 2.83 barns/electron
U=PE_{Montgomeryite} x rElectron 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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Ask about Montgomeryite 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 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: