Pekovite Mineral Data

General Pekovite Information

Chemical Formula:

SrB2Si2O8

Composition:

Molecular Weight = 291.02 gm

Strontium 29.21 % Sr 34.54 % SrO

Silicon 19.49 % Si 41.71 % SiO₂

Boron 7.32 % B 23.56 % B₂O₃

Oxygen 43.98 % O

______ ______

100.00 % 99.81 % = TOTAL OXIDE

Empirical Formula:

Sr_0.97B_1.97Si_2.02O₈

Environment:

Found in a block of quartz, presumably the quartz core of a pegmatite or other type of vein. Sr-dominant analogue of danburite

IMA Status:

Approved IMA 2004 (Dana # Added)

Locality:

Moraine of the Dara-i-Pioz glacier, Alai range, Tien Shan, northern Tajikistan. Link to MinDat.org Location Data.

Name Origin:

Named for Igor Viktorovich Pekov (1967-), Russian mineralogist and alkaline rock expert.

Synonym:

Bonchevite - mixture of pekoite and galenobismutiteBonchevite - mixture of pekoite and galenobismutite

IMA2003-035

Pekovite Image

Images:

Pekovite

Comments: Backscatter elecron image of (a) an intergrowth of pekovite (Pkv) and pectolite (Pct) and (b), an enlarged area of (a) showing details. (CanMin, v 42, p 110).
Location: Moraine of the Dara-i-Pioz glacier, Alai range, Tien Shan, northern Tajikistan. Scale: See Image.
© Canadian Mineralogist

Pekovite Crystallography

Axial Ratios:

a:b:c =1.0298:1:1.1265

Cell Dimensions:

a = 8.155, b = 7.919, c = 8.921, Z = 4; V = 576.11 Den(Calc)= 3.36

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): 3.62(1)(210), 2.786(0.9)(103,013,122), 3.51(0.9)(112),3.31(0.8)(121), 1.982(0.7)(232), 2.706(0.6), 3.01(0.6)(202), 5.94(0.6)(011),

Crystal Structure:

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Pautov L A , Agakhanov A A , Sokolova E V , Hawthorne F C , The Canadian Mineralogist , 42 (2004) p.107-119, Maleevite, BaB2Si2O8, and pekovite, SrB2Si2O8, new mineral species from the, Dara-i-Pioz alkaline massif, Northern Tajikistan: Description and crystal structure, Locality: Dara-i-Pioz alkaline massif, Northern Tajikistan

Physical Properties of Pekovite

Cleavage:

None

Color:

Colorless.

Density:

3.35

Diaphaneity:

Transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Intergrown Crystals - Occurs as intergrown crystalline aggregates

Hardness:

7 - Quartz

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Pekovite

Gladstone-Dale:

CI meas= 0.015 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.018 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1841,KPDmeas= 0.1847,KC= 0.1875
Ncalc = 1.63

Optical Data:

Biaxial (-), a=1.597, b=1.627, g=1.632, bire=0.0350

Calculated Properties of Pekovite

Electron Density:

Bulk Density (Electron Density)=3.20 gm/cc
note: Specific Gravity of Pekovite =3.35 gm/cc.

Fermion Index:

Fermion Index = 0.04
Boson Index = 0.96

Photoelectric:

PE_Pekovite= 33.16 barns/electron
U=PE_Pekovite x rElectron Density= 106.10 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Pekovite is Not Radioactive

Pekovite Classification

Dana Class:

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

(56.03)with [Si2O7] with borate groups

(56.03.01)Danburite Goup

56.03.01.01 Danburite CaB2(SiO4)2 Pnam 2/m 2/m 2/m

56.03.01.02 Maleevite! BaB2Si2O8 P nma 2/m 2/m 2/m

56.03.01.03 Pekovite! SrB2Si2O8 P nma 2/m 2/m 2/m

Strunz Class:

09.FA.65 09 - SILICATES (Germanates)

09.F - Tektosilicates without Zeolitic H2O

09.FA -Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1

09.FA.65 Danburite CaB2(SiO4)2 Pnam 2/m 2/m 2/m

09.FA.65 Maleevite! BaB2Si2O8 P nma 2/m 2/m 2/m

09.FA.65 Pekovite! SrB2Si2O8 P nma 2/m 2/m 2/m

Other Pekovite Information

References:

NAME( CanMin, v 42, p 107) PHYS. PROP.(CanMin, v 42, p 107) OPTIC PROP.(CanMin, v 42, p 107)

See Also:

Links to other databases for Pekovite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Ask about Pekovite here :
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Print or Cut-and-Paste your Pekovite Specimen Label here :

Pekovite

SrB2Si2O8
Dana No: 56.03.01.03 Strunz No: 09.FA.65
Locality:

Notes: