Helvite Mineral Data

Helvite Mineral Data +

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General Helvite Information

Chemical Formula:

Mn4Be3(SiO4)3S

Composition:

Molecular Weight = 555.10 gm

Manganese 39.59 % Mn 51.12 % MnO

Beryllium 4.87 % Be 13.52 % BeO

Silicon 15.18 % Si 32.47 % SiO₂

Sulfur 5.78 % S 5.78 % S^2-

- % S -2.88 % -O=S

Oxygen 34.59 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₄Be₃(SiO₄)₃S

Environment:

Found in skarns, pegmatites, and hydrothermally altered rocks.

IMA Status:

Valid Species (Pre-IMA) 1817

Locality:

Schwarzenberg and Breitenbrunn, Germany. Link to MinDat.org Location Data.

Name Origin:

From the Greek helios - "sun."

Helvite Image

Images:

Helvite Rhodochrosite

Comments: Yellow crystals of helvite on quartz and pink rhodochrosite.
Location: Galerie Elisabeth, Cavnic, Maramures, Romaina. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Helvite

Comments: Large (for the species), triangular yellowish creamy colored crystals of helvite on white, albite matrix.
Location: Navegador mine, Conselheiro Pena, Minas Gerais, Brazil. Scale: Crystal size 0.7 x 0.7 cm.
© Fabre Minerals

Helvite Crystallography

Cell Dimensions:

a = 8.294, Z = 2; V = 570.55 Den(Calc)= 3.23

Crystal System:

Isometric - HextetrahedralH-M Symbol (4 3m) Space Group: P 43n

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

By Intensity(I/I_o): 3.386(1), 1.9549(0.34), 2.623(0.12),

Crystal Structure:

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drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
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Hassan I , Grundy H D , American Mineralogist , 70 (1985) p.186-192, The crystal structures of helvite group minerals, (MnFeZn)8(Be6Si6O24)S2

View Additional jPOWD Structure files for Helvite
[1] [2] [3] [4] [5] [6]

Physical Properties of Helvite

Cleavage:

[111] Indistinct, [111] Indistinct, [111] Indistinct

Color:

Brown, Brownish yellow, Gray, Yellow, Yellow green.

Density:

3.16 - 3.36, Average = 3.26

Diaphaniety:

Translucent to opaque

Fracture:

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

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luminescence:

None.

Luster:

Vitreous - Resinous

Streak:

grayish white

Optical Properties of Helvite

Gladstone-Dale:

CI meas= -0.127 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.138 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2283,KPDmeas= 0.2262,KC= 0.2007

Optical Data:

Isotropic, n=1.728-1.747.

Calculated Properties of Helvite

Electron Density:

r_electron=3.12 gm/cc
note: r_Helvite=3.26 gm/cc.

Fermion Index

Fermion Index = 0.05639
Boson Index = 0.94361

Photoelectric:

PE_Helvite= 11.15 barns/electron
U=PE_Helvite x r_electron= 34.82 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Helvite is Not Radioactive

Helvite Classification

Dana Class:

76.2.4.1 (76)Tectosilicate Al-Si Framework

(76.2)Feldspathoids and related species

(76.2.4)Helvite group

76.2.4.1 Helvite Mn4Be3(SiO4)3S P 43n 4 3m

76.2.4.2 Danalite Fe4Be3(SiO4)3S P 43n 4 3m

76.2.4.3 Genthelvite Zn4Be3(SiO4)3S P 43n 4 3m

Strunz Class:

VIII/J.12-20 VIII - Silicates

VIII/J - Tectosilicates (network) with anions unfamiliar to the tetraheders

VIII/J.12 - Sodalite group, Danalite - Genthelvite series

VIII/J.12-10 Danalite Fe4Be3(SiO4)3S P 43n 4 3m

VIII/J.12-20 Helvite Mn4Be3(SiO4)3S P 43n 4 3m

VIII/J.12-30 Genthelvite Zn4Be3(SiO4)3S P 43n 4 3m

Other Helvite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Helvite

Mn4Be3(SiO4)3S
Dana No: 76.2.4.1 Strunz No: VIII/J.12-20
Locality:

Notes: