Brushite Mineral Data

Brushite Mineral Data +

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General Brushite Information

Chemical Formula:

CaHPO4·2(H2O)

Composition:

Molecular Weight = 172.09 gm

Calcium 23.29 % Ca 32.59 % CaO

Phosphorus 18.00 % P 41.24 % P₂O₅

Hydrogen 2.93 % H 26.17 % H₂O

Oxygen 55.78 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca(HPO₄)·2(H₂O)

Environment:

One of the most common cave minerals, in guano deposits, and in phosphorites, formed at low pH by reaction of phosphate-rich solutions with calcite and clay.

IMA Status:

Valid Species (Pre-IMA) 1865

Locality:

Found on Aves Island, Venezuela, west of Dominica, in the Caribbean Sea. Link to MinDat.org Location Data.

Name Origin:

To honor Professor George Jarvis Brush (1831-1912), American mineralogist, Yale University, New Haven, Connecticut, USA.

Synonym:

ICSD 16132

PDF 11-293

Brushite Image

Images:

Brushite

Comments: Tan coatings of brushite on calcite.
Location: Oberschleme, Erzgebirge Mountains, Sachsen, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Brushite Crystallography

Axial Ratios:

a:b:c =0.3881:1:0.4204

Cell Dimensions:

a = 5.88, b = 15.15, c = 6.37, Z = 4; beta = 117.467° V = 503.49 Den(Calc)= 2.27

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: I2/a

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

By Intensity(I/I_o): 7.62(1), 3.8(0.3), 1.9(0.1),

Crystal Structure:

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Schofield P F , Knight K S , van der Houwen J A M , Valsami-Jones E , Physics and Chemistry of Minerals , 31 (2004) p.606-624, The role of hydrogen bonding in the thermal expansion and dehydration, of brushite, di-calcium phosphate dihydrate, Sample: T = 4.2 K

View Additional jPOWD Structure files for Brushite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Brushite

Cleavage:

[010] Perfect, [001] Perfect

Color:

Colorless, Yellow, Yellowish white, White.

Density:

2.328

Diaphaniety:

Transparent to Translucent

Hardness:

2.5 - Finger Nail

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Brushite

Gladstone-Dale:

CI meas= -0.006 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.032 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2402,KPDmeas= 0.2342,KC= 0.2329

Optical Data:

Biaxial (+), a=1.539, b=1.546, g=1.551, bire=0.0120, 2V(Calc)=80, 2V(Meas)=86.

Calculated Properties of Brushite

Electron Density:

r_electron=2.38 gm/cc
note: r_Brushite=2.33 gm/cc.

Fermion Index

Fermion Index = 0.00058
Boson Index = 0.99942

Photoelectric:

PE_Brushite= 3.72 barns/electron
U=PE_Brushite x r_electron= 8.85 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Brushite is Not Radioactive

Brushite Classification

Dana Class:

39.1.1.1 (39)Hydrated Acid Phosphates, etc

(39.1)A+ [HXO4] · x(H2O)

(39.1.1)Dana Group

39.1.1.1 Brushite CaHPO4·2(H2O) I2/a 2/m

39.1.1.2 Pharmacolite CaHAsO4·2(H2O) Ia m

Strunz Class:

VII/C.25-10 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions, cations of medium and big size: Fe, Mn, Zn, Mg and Ca, (NH4)1+

VII/C.25 - Brushite - Churchite-(Dy) series

VII/C.25-10 Brushite CaHPO4·2(H2O) I2/a 2/m

VII/C.25-20 Pharmacolite CaHAsO4·2(H2O) Ia m

VII/C.25-30 Churchite-(Y) YPO4·2(H2O) A2/a,Aa Mono

VII/C.25-40 Churchite-(Nd)! Nd(PO4)·2(H2O) Mono

VII/C.25-50 Churchite-(Dy)* (Dy,Sm,Gd,Nd)(PO4)·2(H2O) Mono

Other Brushite Information

References:

NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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

Brushite

CaHPO4·2(H2O)
Dana No: 39.1.1.1 Strunz No: VII/C.25-10
Locality:

Notes: