Acuminite Mineral Data

Acuminite Mineral Data +

General Acuminite Information

Chemical Formula:

SrAlF4(OH)·(H2O)

Composition:

Molecular Weight = 225.62 gm

Strontium 38.84 % Sr 45.93 % SrO

Aluminum 11.96 % Al 22.60 % Al₂O₃

Hydrogen 1.34 % H 11.98 % H₂O

Oxygen 14.18 % O

Fluorine 33.68 % F 33.68 % F

- % F -14.18 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

SrAlF₄(OH)·(H₂O)

Environment:

In the Ivigtut cryolite deposit, southwestern Greenland.

IMA Status:

Approved IMA 1987

Locality:

Greenland, Ivigtut Link to MinDat.org Location Data.

Name Origin:

From the Latin acuminis, sharp point, for spear head, the characteristic shape of the crystals.

Synonym:

ICSD 33830

PDF 48-1870

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Acuminite Crystallography

Axial Ratios:

a:b:c =2.5551:1:2.7538

Cell Dimensions:

a = 13.223, b = 5.175, c = 14.251, Z = 8; beta = 111.61° V = 906.64 Den(Calc)= 3.31

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): 3.5049(1), 4.7058(1), 4.7674(1),

Crystal Structure:

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Krogh Andersen E , Ploug-Sorensen G , Leonardsen E , Zeitschrift fur Kristallographie , 194 (1991) p.221-227, The structure of acuminite, a strontium aluminium fluoride mineral, Locality: Ivigtut, Greenland

Physical Properties of Acuminite

Cleavage:

[???] Perfect

Color:

Colorless.

Density:

3.295

Diaphaniety:

Transparent

Hardness:

3.5 - Copper Penny

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Acuminite

Gladstone-Dale:

CI meas= 0.187 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.19 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1376,KPDmeas= 0.1382,KC= 0.1699

Optical Data:

Biaxial (+), a=1.4507, b=1.4528, g=1.4624-1.4627, bire=0.0117-0.0120, 2V(Calc)=50-52, 2V(Meas)=46-57.

Calculated Properties of Acuminite

Electron Density:

r_electron=3.10 gm/cc
note: r_Acuminite=3.30 gm/cc.

Fermion Index

Fermion Index = 0.02725
Boson Index = 0.97275

Photoelectric:

PE_Acuminite= 44.23 barns/electron
U=PE_Acuminite x r_electron= 136.93 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Acuminite is Not Radioactive

Acuminite Classification

Dana Class:

11.6.17.1 (11)Halide Complexes; Alumino-fluorides

(11.6)with miscellaneous formulae

(11.6.17)Dana Group

11.6.17.1 Acuminite SrAlF4(OH)·(H2O) C 2/c 2/m

Strunz Class:

III/C.01-20 III - Halogenides

III/C - Double halogenides with water, Fluorides

III/C.01 - Gearksutite - Chukhrovite - (Ce) series

III/C.01-10 Gearksutite CaAl(OH,F)5·(H2O) Mono

III/C.01-20 Acuminite SrAlF4(OH)·(H2O) C 2/c 2/m

III/C.01-30 Tikhonenkovite SrAl(OH)F4·(H2O) Unk Mono

III/C.01-35 Artroeite PbAlF3(OH)2 P1 1

III/C.01-40 Creedite Ca3Al2(SO4)(F,OH)10·2(H2O) C 2/c 2/m

III/C.01-50 Chukhrovite-(Y) Ca3(Y,Ce)Al2(SO4)F13·10(H2O) F d3 2/m 3

III/C.01-60 Chukhrovite-(Ce) Ca3(Ce,Y)Al2(SO4)F13·10(H2O) F d3 2/m 3

Other Acuminite Information

References:

NAME( AntBidBlaNic3) PHYS. PROP.(Am.Min.,Vol.73,p1492,1988) OPTIC PROP.(Am.Min.,Vol.73,p1492,1988)

See Also:

Links to other databases for Acuminite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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Acuminite

SrAlF4(OH)·(H2O)
Dana No: 11.6.17.1 Strunz No: III/C.01-20
Locality:

Notes: