Merwinite Mineral Data

Merwinite Mineral Data +

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General Merwinite Information

Chemical Formula:

Ca3Mg(SiO4)2

Composition:

Molecular Weight = 328.71 gm

Calcium 36.58 % Ca 51.18 % CaO

Magnesium 7.39 % Mg 12.26 % MgO

Silicon 17.09 % Si 36.56 % SiO₂

Oxygen 38.94 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃Mg(SiO₄)₂

Environment:

Metamorphosed limestone.

IMA Status:

Valid Species (Pre-IMA) 1921

Locality:

Crestmore quarry, 5 miles NW of Riverside, Riverside Co., California. Link to MinDat.org Location Data.

Synonym:

ICSD 26002

PDF 35-591

Merwinite Image

Images:

Merwinite

Comments: Dark brown crystalline merwinite in light green crystalline massive marble.
Location: Crestmore Quarry, Riverside County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Merwinite Crystallography

Axial Ratios:

a:b:c =2.504:1:1.7623

Cell Dimensions:

a = 13.254, b = 5.293, c = 9.328, Z = 4; beta = 91.9° V = 654.03 Den(Calc)= 3.34

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/a

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

By Intensity(I/I_o): 2.6865(1), 2.6712(0.65), 2.653(0.47),

Crystal Structure:

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Moore P B , Araki T , American Mineralogist , 57 (1972) p.1355-1374, Atomic arrangement of merwinite, Ca3Mg[SiO4]2, an unusual dense-packed, structure of geophysical interest

Physical Properties of Merwinite

Cleavage:

[010] Perfect

Color:

Colorless, Gray, Pale green.

Density:

3.15

Diaphaniety:

Transparent to translucent

Fracture:

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

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

6 - Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Merwinite

Gladstone-Dale:

CI meas= -0.088 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.026 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2135,KPDmeas= 0.2264,KC= 0.208

Optical Data:

Biaxial (+), a=1.706-1.708, b=1.711-1.712, g=1.718-1.724, bire=0.0120-0.0160, 2V(Calc)=62-82, 2V(Meas)=67. Dispersion r > v.

Calculated Properties of Merwinite

Electron Density:

r_electron=3.33 gm/cc
note: r_Merwinite=3.34 gm/cc.

Fermion Index

Fermion Index = 0.01605
Boson Index = 0.98395

Photoelectric:

PE_Merwinite= 5.30 barns/electron
U=PE_Merwinite x r_electron= 17.66 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Merwinite is Not Radioactive

Merwinite Classification

Dana Class:

51.4.2.1 (51)Nesosilicate Insular SiO4 Groups Only

(51.4)with cations in [6] and >[6] coordination

(51.4.2)Dana Group

51.4.2.1 Merwinite Ca3Mg(SiO4)2 P 2₁/a 2/m

Strunz Class:

VIII/A.07-10 VIII - Silicates

VIII/A - Nesosilicates with [SiO4]4-groups, cations of octahedral orientation [6]

VIII/A.07 - Larnite series

VIII/A.07-10 Merwinite Ca3Mg(SiO4)2 P 2₁/a 2/m

VIII/A.07-20 Bredigite Ca7Mg(SiO4)4 P 2nn mm2

VIII/A.07-30 Larnite Ca2SiO4 P 2₁/n 2/m

Other Merwinite Information

References:

NAME( MinRec) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Merwinite

Ca3Mg(SiO4)2
Dana No: 51.4.2.1 Strunz No: VIII/A.07-10
Locality:

Notes: