Microsommite Mineral Data

Microsommite Mineral Data +

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General Microsommite Information

Chemical Formula:

(Na,Ca,K)7-8(Si,Al)12O24(Cl,SO4)2-3

Composition:

Molecular Weight = 1,086.58 gm

Potassium 3.24 % K 3.90 % K₂O

Sodium 8.89 % Na 11.98 % Na₂O

Calcium 9.96 % Ca 13.93 % CaO

Aluminum 16.14 % Al 30.50 % Al₂O₃

Silicon 14.22 % Si 30.41 % SiO₂

Sulfur 2.07 % S 5.16 % SO₃

Chlorine 7.50 % Cl 7.50 % Cl

- % Cl -1.69 % -O=Cl₂

Oxygen 37.99 % O

______ ______

100.00 % 101.69 % = TOTAL OXIDE

Empirical Formula:

Na_4.2Ca_2.7K_0.9Al_6.5Si_5.5O₂₃Cl_2.3(SO₄)_0.7

Environment:

In ejected volcanic masses and in leucitites.

IMA Status:

Valid Species (Pre-IMA) 1872

Locality:

Mte Somma, Vesuvius, Italy. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Microsommite Image

Images:

Microsommite

Comments: Colorless prismatic microsommite microcrystals in vug.
Location: Novella Quarry, Vesuvius, Naples, Campania, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Microsommite

Comments: White acycular microsommite crystals (one mm. long) in small vugs in matrix.
Location: Monte Somma - Vesuvio - NA, Campania, Italy. Scale: Picture size 1 cm.
© Sandro Maggia/Minernet.it

Microsommite Crystallography

Axial Ratios:

a:c = 1:0.24139

Cell Dimensions:

a = 22.08, c = 5.33, Z = 3; V = 2,250.38 Den(Calc)= 2.41

Crystal System:

Hexagonal - TrapezohedralH-M Symbol (6 2 2) Space Group: P 6₃22

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

By Intensity(I/I_o): 3.29(1), 3.69(1), 4.81(1),

Forms:

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Forms: [ 1 1 1] [ 1 1 0] [ 0 1 0] [ 0 0 1]

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Crystal Structure:

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Bonaccorsi E , Comodi P , Merlino S , Physics and Chemistry of Minerals , 22 (1995) p.367-374, Thermal behaviour of davyne-group minerals, Sample: T = 293 K

View Additional jPOWD Structure files for Microsommite
[1] [2]

Physical Properties of Microsommite

Cleavage:

[1010] Perfect, [0001] Distinct

Color:

Colorless, White.

Density:

2.42 - 2.53, Average = 2.47

Diaphaniety:

Transparent

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

6 - Orthoclase

Luster:

Vitreous - Silky

Streak:

white

Optical Properties of Microsommite

Gladstone-Dale:

CI meas= 0.031 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.005 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2178,KPDmeas= 0.2121,KC= 0.2189

Optical Data:

Uniaxial (+), w=1.521, e=1.529, bire=0.0080.

Calculated Properties of Microsommite

Electron Density:

r_electron=2.38 gm/cc
note: r_Microsommite=2.41 gm/cc.

Fermion Index

Fermion Index = 0.00711
Boson Index = 0.99289

Photoelectric:

PE_Microsommite= 3.32 barns/electron
U=PE_Microsommite x r_electron= 7.88 barns/cc.

Radioactivity:

GRapi = 46.04 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Microsommite - barely detectable

Microsommite Classification

Dana Class:

76.2.5.10 (76)Tectosilicate Al-Si Framework

(76.2)Feldspathoids and related species

(76.2.5)Cancrinite group

76.2.5.1 Afghanite (Na,Ca,K)8(Si,Al)12O24(SO4,Cl,CO3)3·(H2O) P 6₃/mmc, P 6₃mc, or P 62c Hex

76.2.5.2 Bystrite (Na,K)7Ca(Si6Al6)O24S4.5·(H2O) P 3₁c 3m

76.2.5.3 Cancrinite Na6Ca2Al6Si6O24(CO3)2 P 6₃ 6

76.2.5.4 Cancrisilite Na7Al5Si7O24(C03)·3(H2O) P 6₃ 6

76.2.5.5 Davyne Na4K2Ca2Si6Al6O24(SO4)Cl2 P 6₃/m 6/m

76.2.5.6 Franzinite [(Na,K)30Ca10][Si30Al30O120](SO4)10·2(H2O) P 3₂1 3 2

76.2.5.7 Giuseppettite [Na42K16Ca6]S64Si48Al48O192(SO4)10Cl2·5H2O P 3₁c 3m

76.2.5.8 Hydroxycancrinite Na4(AlSiO4)3(OH)·(H2O) P 6₃ 6

76.2.5.9 Liottite (Ca,Na,K)8(Si,Al)12O24[(SO4),(CO3),Cl,OH]4·(H2O) P 6m2 6 m2

76.2.5.10 Microsommite (Na,Ca,K)7-8(Si,Al)12O24(Cl,SO4)2-3 P 6₃22 6 2 2

76.2.5.11 Pitiglianoite Na6K2Si6Al6O24(SO4)·2(H2O) P 6₃ 6

76.2.5.12 Quadridavyne (Na,K)6Ca2Al6Si6O24Cl4 P 6₃/m 6/m

76.2.5.13 Sacrofanite (Na,Ca,K)9Si6Al6O24[(OH),(SO4),(CO3),Cl)]4·n(H2O) P 6₃/mmc ? 6/m 2/m 2/m

76.2.5.14 Tounkite (Na,Ca,K)8Al6Si6O24(SO4)2Cl·(H2O) P 6₂22 6 2 2

76.2.5.15 Vishnevite (Na,Ca,K)6(Si,Al)12O24[(SO4),(CO3),Cl2]2-4·n(H2O) P 6₃22 6 2 2

76.2.5.16 Wenkite Ba4Ca6(Si,Al)20O39(OH)2(SO4)3·n(H2O)(?) P 62m 6 m2

76.2.5.17 Marinellite! [(Na,K)42Ca6](Si36Al36O144)(SO4)8Cl2·6(H2O) P 3₁c or P 2c Trig

76.2.5.18 IMA2004-043! (Na37K9Ca10)S56(Si42Al42)S84O168(SO4)12·6(H2O) P 6₃/m 6/m 2/m 2/m

Strunz Class:

VIII/J.09-30 VIII - Silicates

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

VIII/J.09 - Cancrinite group

VIII/J.09-05 Hydroxycancrinite Na4(AlSiO4)3(OH)·(H2O) P 6₃ 6

VIII/J.09-10 Cancrinite Na6Ca2Al6Si6O24(CO3)2 P 6₃ 6

VIII/J.09-15 Cancrisilite Na7Al5Si7O24(C03)·3(H2O) P 6₃ 6

VIII/J.09-20 Davyne Na4K2Ca2Si6Al6O24(SO4)Cl2 P 6₃/m 6/m

VIII/J.09-25 Quadridavyne (Na,K)6Ca2Al6Si6O24Cl4 P 6₃/m 6/m

VIII/J.09-30 Microsommite (Na,Ca,K)7-8(Si,Al)12O24(Cl,SO4)2-3 P 6₃22 6 2 2

VIII/J.09-40 Giuseppettite [Na42K16Ca6]S64Si48Al48O192(SO4)10Cl2·5H2O P 3₁c 3m

VIII/J.09-45 Bystrite (Na,K)7Ca(Si6Al6)O24S4.5·(H2O) P 3₁c 3m

VIII/J.09-50 Afghanite (Na,Ca,K)8(Si,Al)12O24(SO4,Cl,CO3)3·(H2O) P 6₃/mmc, P 6₃mc, or P 62c Hex

VIII/J.09-55 Tounkite (Na,Ca,K)8Al6Si6O24(SO4)2Cl·(H2O) P 6₂22 6 2 2

VIII/J.09-60 Sacrofanite (Na,Ca,K)9Si6Al6O24[(OH),(SO4),(CO3),Cl)]4·n(H2O) P 6₃/mmc ? 6/m 2/m 2/m

VIII/J.09-65 Pitiglianoite Na6K2Si6Al6O24(SO4)·2(H2O) P 6₃ 6

VIII/J.09-70 Vishnevite (Na,Ca,K)6(Si,Al)12O24[(SO4),(CO3),Cl2]2-4·n(H2O) P 6₃22 6 2 2

VIII/J.09-80 Franzinite [(Na,K)30Ca10][Si30Al30O120](SO4)10·2(H2O) P 3₂1 3 2

VIII/J.09-90 Liottite (Ca,Na,K)8(Si,Al)12O24[(SO4),(CO3),Cl,OH]4·(H2O) P 6m2 6 m2

VIII/J.09-100 Wenkite Ba4Ca6(Si,Al)20O39(OH)2(SO4)3·n(H2O)(?) P 62m 6 m2

Other Microsommite Information

References:

NAME( Ford32) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(Ford32)

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Microsommite

(Na,Ca,K)7-8(Si,Al)12O24(Cl,SO4)2-3
Dana No: 76.2.5.10 Strunz No: VIII/J.09-30
Locality:

Notes: