Sphaerobertrandite Mineral Data

Sphaerobertrandite Mineral Data +

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General Sphaerobertrandite Information

Chemical Formula:

Be3SiO4(OH)2

Composition:

Molecular Weight = 152.62 gm

Beryllium 17.07 % Be 47.36 % BeO

Silicon 18.59 % Si 39.76 % SiO₂

Hydrogen 1.45 % H 12.93 % H₂O

Oxygen 62.90 % O

______ ______

100.00 % 100.05 % = TOTAL OXIDE

Empirical Formula:

Be_2.89Si_1.01O_3.81(OH)_2.19

Environment:

Found in Be-bearing pegmatites and greisens. Originally named in 1957 and revalidated in 2003.

IMA Status:

Valid Species (Pre-IMA) 1957 (Dana # Added)

Locality:

Mannepakhk Mountain,Lovozero massif, Russia. Link to MinDat.org Location Data.

Name Origin:

The name alludes to the typical spherulitic morphology and the similarity to bertrandite in the main chemical constituents.

Sphaerobertrandite Image

Images:

Sphaerobertrandite

Comments: White to pale brownish, radial-concentric aggregates of sphaerobertrandite.
Location: Sengischorr Mt, Lovozero Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Sphaerobertrandite Crystallography

Axial Ratios:

a:b:c =1.0952:1:3.8077

Cell Dimensions:

a = 5.081, b = 4.639, c = 17.664, Z = 4; beta = 106.09° V = 400.04 Den(Calc)= 2.53

Crystal System:

Monoclinic - SphenoidalH-M Symbol (2) Space Group: P 2

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

By Intensity(I/I_o): 3.161(1)(111,113), 2.318(0.9)(020), 4.885(0.9)(100),2.836(0.7)(104), 4.236(0.62)(004),

Crystal Structure:

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Pekov I V , Chukanov N V , Larsen A O , Merlino S , Pasero M , Pushcharovsky D Y , Ivaldi G , Zadov A E , Grishin V G , Asheim A , Tafto J , Chistyakova N I , European Journal of Mineralogy , 15 (2003) p.157-166, Sphaerobertrandite, Be3SiO4(OH)2: new data, crystal structure and genesis

Physical Properties of Sphaerobertrandite

Cleavage:

[001] Perfect, [010] Distinct

Color:

Colorless, Yellow, Brownish white, White, Gray.

Density:

2.46 - 2.54, Average = 2.5

Diaphaniety:

Transparent to Translucent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Platy - Sheet forms (e.g. micas).

Habit:

Spherical - Spherical, rounded aggregates.

Hardness:

5 - Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Sphaerobertrandite

Gladstone-Dale:

CI meas= -0.01 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.002 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2398,KPDmeas= 0.2427,KC= 0.2403

Optical Data:

Biaxial (-), a=1.597, b=1.607, g=1.616, bire=0.0190, 2V(Calc)=86, 2V(Meas)=86.5. Dispersion none.

Calculated Properties of Sphaerobertrandite

Electron Density:

r_electron=2.52 gm/cc
note: r_{Sphaerobertrandite}=2.53 gm/cc.

Fermion Index

Fermion Index = 0.17964
Boson Index = 0.82036

Photoelectric:

PE_{Sphaerobertrandite}= 0.91 barns/electron
U=PE_{Sphaerobertrandite} x r_electron= 2.29 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Sphaerobertrandite is Not Radioactive

Sphaerobertrandite Classification

Dana Class:

52.1.2.1 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.1)with cations in [4] coordination

(52.1.2)Dana Group

52.1.2.1 Sphaerobertrandite ! Be3SiO4(OH)2 P 2 2

Strunz Class:

VIII/B.01-25 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]

VIII/B.01 - Euclase series

VIII/B.01-10 Euclase BeAlSiO4(OH) P 2₁/a 2/m

VIII/B.01-20 Hodgkinsonite MnZn2SiO4(OH)2 P 2₁/c 2/m

VIII/B.01-25 Sphaerobertrandite Be3SiO4(OH)2 P 2 2

VIII/B.01-30 Beryllite Be3SiO4(OH)2·(H2O) Unk Ortho

Other Sphaerobertrandite Information

References:

NAME( AmMin, v 88, p 1839) PHYS. PROP.(AmMin, v 88, p 1839) OPTIC PROP.(AmMin, v 88, p 1839)

See Also:

Links to other databases for Sphaerobertrandite :
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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Sphaerobertrandite

Be3SiO4(OH)2
Dana No: 52.1.2.1 Strunz No: VIII/B.01-25
Locality:

Notes: