Bigcreekite Mineral Data

Bigcreekite Mineral Data

General Bigcreekite Information

Chemical Formula:

BaSi2O5·4(H2O)

Composition:

Molecular Weight = 345.56 gm

Barium 39.74 % Ba 44.37 % BaO

Silicon 16.26 % Si 34.78 % SiO₂

Hydrogen 2.33 % H 20.85 % H₂O

Oxygen 41.67 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BaSi₂O₅·4(H₂O)

Environment:

Found in fractures in a sanborite-quartz gneiss. Double-chain silicate; structure.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Esquire no. 7 claim, along Big Creek, Fresno County, California, USA. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

IMA1999-015

Bigcreekite Image

Images:

Bigcreekite Gillespite Sanbornite

Comments: Tiny white, spherical patterns, halo-like crystals of bigcreekite to about 0.5mm and reddish gillespite in a matrix of pale yellowish sanbornite.
Location: Trumbull Peak, Mariposa Co., California, United States. Scale: 2.5 x 2 x 2cm.
© Tom Loomis / Dakota Matrix

Bigcreekite Crystallography

Axial Ratios:

a:b:c =0.5582:1:2.0302

Cell Dimensions:

a = 5.038, b = 9.024, c = 18.321, Z = 4; V = 832.93 Den(Calc)= 2.76

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P nma

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

By Intensity(I/I_o): 5.068(1)(013), 4.054(0.85)(022), 2.257(0.75)(126),2.706(0.6)(124), 2.974(0.45)(031), 2.327(0.4)(035), 9.19(0.3),

Crystal Structure:

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Basciano L C , Groat L A , Roberts A C , Gault R A , Dunning G E , Walstrom R E , The Canadian Mineralogist , 39 (2001) p.761-768, Bigcreekite: A new barium silicate mineral species from Fresno County, California, Locality: Fresno County, California, USA

Physical Properties of Bigcreekite

Cleavage:

[001] Perfect, [010] Perfect

Color:

Colorless, White.

Density:

2.66

Diaphaniety:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Subhedral Crystals - Occurs as crystals which tend to exhibit a recognizable crystal shape.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

2-3 - Gypsum-Calcite

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Bigcreekite

Gladstone-Dale:

CI meas= -0.012 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.024 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1952,KPDmeas= 0.2025,KC= 0.2

Optical Data:

Biaxial (+), a=1.537, b=1.538, g=1.541, bire=0.0040, 2V(Calc)=62, 2V(Meas)=59.2. Dispersion r < v moderate.

Calculated Properties of Bigcreekite

Electron Density:

r_electron=2.52 gm/cc
note: r_Bigcreekite=2.66 gm/cc.

Fermion Index

Fermion Index = 0.07862
Boson Index = 0.92138

Photoelectric:

PE_Bigcreekite= 168.55 barns/electron
U=PE_Bigcreekite x r_electron= 425.58 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Bigcreekite is Not Radioactive

Bigcreekite Classification

Dana Class:

66.2.1.2 (66)Inosilicate Double-Width Unbranched Chains, W=2

(66.2)with P=2 non-amphibole configuration

(66.2.1)Dana Group

66.2.1.1 Plancheite Cu8Si8O22(OH)4·(H2O) Pcnb 2/m 2/m 2/m

66.2.1.2 Bigcreekite ! BaSi2O5·4(H2O) P nma 2/m 2/m 2/m

Strunz Class:

VIII/H.02-60 VIII - Silicates

VIII/H - Phyllosilicates (layered), Tetragonal or pseudotetragonal layered structures [Si4O10]4- and others

VIII/H.02 - Davanite - Dalyite series

VIII/H.02-10 Cuprorivaite CaCuSi4O10 P 4/nnc 4/m 2/m 2/m

VIII/H.02-20 Wesselsite! SrCuSi4O10 P 4/ncc 4/m 2/m 2/m

VIII/H.02-30 Effenbergerite BaCuSi4O10 P 4/nnc 4/m 2/m 2/m

VIII/H.02-40 Gillespite BaFeSi4O10 P 4/ncc 4/m 2/m 2/m

VIII/H.02-50 Sanbornite BaSi2O5 Pmnb 2/m 2/m 2/m

VIII/H.02-60 Bigcreekite BaSi2O5·4(H2O) P nma 2/m 2/m 2/m

Other Bigcreekite Information

References:

NAME( AmMin, Vol 87, p 355) PHYS. PROP.(AmMin, Vol 87, p 355) OPTIC PROP.(AmMin, Vol 87, p 355)

See Also:

Links to other databases for Bigcreekite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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

Bigcreekite

BaSi2O5·4(H2O)
Dana No: 66.2.1.2 Strunz No: VIII/H.02-60
Locality:

Notes: