Foshallasite Mineral Data

Foshallasite Mineral Data +

General Foshallasite Information

Chemical Formula:

Ca3Si2O7·3(H2O)

Composition:

Molecular Weight = 342.45 gm

Calcium 35.11 % Ca 49.13 % CaO

Silicon 16.40 % Si 35.09 % SiO₂

Hydrogen 1.77 % H 15.78 % H₂O

Oxygen 46.72 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃Si₂O₇·3(H₂O)

Environment:

Alkaline nepheline syenites.

IMA Status:

Valid Species (Pre-IMA) 1936

Locality:

Mt. Yukspor, Khibiny massif, Kola Peninsula, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for Willian Frederick Foshag (1984-1956), American mineralogist, and for the mineral centrallasite (now named gyrolite).

Foshallasite Image

Images:

Foshallasite

Comments: Pearly translucent white somewhat fibrous aggregate of foshallasite.
Location: Mount Yukspor, Khibiny Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Foshallasite Crystallography

Crystal System:

Monoclinic

Physical Properties of Foshallasite

Cleavage:

[100] Perfect

Color:

Snow white.

Density:

2.5

Hardness:

2.5-3 - Finger Nail-Calcite

Streak:

white

Optical Properties of Foshallasite

Gladstone-Dale:

CI meas= 0.057 (Good) - where the CI = (1-KPDmeas/KC)
KPDmeas= 0.2168,KC= 0.2298

Optical Data:

Biaxial (-), a=1.535, b=1.542, g=1.549, bire=0.0140, 2V(Calc)=88, 2V(Meas)=12-18.

Calculated Properties of Foshallasite

Electron Density:

r_electron=2.54 gm/cc
note: r_Foshallasite=2.50 gm/cc.

Fermion Index

Fermion Index = 0.00836
Boson Index = 0.99164

Photoelectric:

PE_Foshallasite= 4.90 barns/electron
U=PE_Foshallasite x r_electron= 12.46 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Foshallasite is Not Radioactive

Foshallasite Classification

Dana Class:

56.2.9.3 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.2)with cations in [4] and/or >[4] coordination

(56.2.9)Tilleyite - Killalaite group

56.2.9.1 Tilleyite Ca5Si2O7(CO3)2 P 2₁/a 2/m

56.2.9.2 Killalaite 2Ca3Si2O7·(H2O) P 2₁/m 2/m

56.2.9.3 Foshallasite Ca3Si2O7·3(H2O) Mono

Strunz Class:

VIII/C.09-60 VIII - Silicates

VIII/C - Sorosilicates with [Si2O7]6-, with anions unfamiliar to tetraheders [O,OH,F]

VIII/C.09 - Tilleyite - Foshallasite series

VIII/C.09-20 Tilleyite Ca5Si2O7(CO3)2 P 2₁/a 2/m

VIII/C.09-30 Jaffeite Ca4(Si3O7)(OH)6 P 3 3

VIII/C.09-40 Suolunite Ca2Si2O5(OH)2·(H2O) F dd2 mm2

VIII/C.09-50 Killalaite 2Ca3Si2O7·(H2O) P 2₁/m 2/m

VIII/C.09-60 Foshallasite Ca3Si2O7·3(H2O) Mono

Other Foshallasite 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 Foshallasite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -MinDAT 7 -MinMax(Deutsch) 8 -MinMax(English) 9 -Mineralienatlas (Deutsch) 10 -QUT Mineral Atlas 11 -École des Mines de Paris

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

Foshallasite

Ca3Si2O7·3(H2O)
Dana No: 56.2.9.3 Strunz No: VIII/C.09-60
Locality:

Notes: