Pecoraite Mineral Data

Pecoraite Mineral Data +

General Pecoraite Information

Chemical Formula:

Ni3Si2O5(OH)4

Composition:

Molecular Weight = 380.27 gm

Silicon 14.77 % Si 31.60 % SiO₂

Nickel 46.30 % Ni 58.92 % NiO

Hydrogen 1.06 % H 9.48 % H₂O

Oxygen 37.87 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ni₃SI₂O₅(OH)₄

IMA Status:

Approved IMA 1969

Locality:

Link to MinDat.org Location Data.

Synonym:

Chrysotile(Ni)

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Pecoraite Crystallography

Axial Ratios:

a:b:c =0.5742:1:1.6048

Cell Dimensions:

a = 5.26, b = 9.16, c = 14.7, Z = 4; beta = 92° V = 707.84 Den(Calc)= 3.57

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 7.43(1), 1.529(0.8), 3.66(0.8),

Physical Properties of Pecoraite

Color:

Dark green.

Density:

3.84 - 3.084, Average = 3.46

Diaphaniety:

Translucent

Hardness:

2.5 - Finger Nail

Streak:

light green

Optical Properties of Pecoraite

Gladstone-Dale:

CI meas= 0.173 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.198 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1618,KPDmeas= 0.1669,KC= 0.2017

Optical Data:

Biaxial (+/-), a=1.565, b=1.565-1.603, g=1.565-1.603, bire=0.0000-0.0380, 2V(Calc)=0, 2V(Meas)=0.

Calculated Properties of Pecoraite

Electron Density:

r_electron=3.42 gm/cc
note: r_Pecoraite=3.46 gm/cc.

Fermion Index

Fermion Index = 0.01231
Boson Index = 0.98769

Photoelectric:

PE_Pecoraite= 18.77 barns/electron
U=PE_Pecoraite x r_electron= 64.27 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Pecoraite is Not Radioactive

Pecoraite Classification

Dana Class:

71.1.2d.4 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.1)with 1:1 layers

(71.1.2d)Serpentine group (Chrysotile subgroup)

71.1.2d.0 Chrysotile! Mg3Si2O5(OH)4 A2/m 2/m

71.1.2d.1 Clinochrysotile Mg3Si2O5(OH)4 Cc, C 2/m Mono

71.1.2d.2 Orthochrysotile Mg3Si2O5(OH)4 Unk Ortho

71.1.2d.3 Parachrysotile Mg3Si2O5(OH)4 Unk Ortho

71.1.2d.4 Pecoraite Ni3Si2O5(OH)4 C 2/m 2/m

Strunz Class:

VIII/H.27-160 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like with [Si4O10]4- and related groups

VIII/H.27 - Serpentine group

VIII/H.27-10 Antigorite (Mg,Fe)3Si2O5(OH)4 Cm m

VIII/H.27-20 Lizardite Mg3Si2O5(OH)4 P1 1

VIII/H.27-30 Clinochrysotile Mg3Si2O5(OH)4 Cc, C 2/m Mono

VIII/H.27-40 Orthochrysotile Mg3Si2O5(OH)4 Unk Ortho

VIII/H.27-50 Parachrysotile Mg3Si2O5(OH)4 Unk Ortho

VIII/H.27-55 Caryopilite (Mn,Mg,Zn,Fe)3(Si,As)2O510(OH,Cl)4 Cm or C 2/m Mono

VIII/H.27-60 Greenalite (Fe,Fe)2-3Si2O5(OH)4 Unk Mono

VIII/H.27-70 Berthierine (Fe,Fe,Al,Mg)2-3(Si,Al)2O5(OH)4 Cm m

VIII/H.27-80 Fraipontite (Zn,Al)3(Si,Al)2O5(OH)4 Cm m

VIII/H.27-90 Zinalsite Zn2AlSi2O5(OH)4·2(H2O)(?) Mono

VIII/H.27-95 Dozyite (Mg7Al2)(Si4Al2)O15(OH)12 Cm m

VIII/H.27-100 Amesite Mg2Al(SiAl)O5(OH)4 C1 1

VIII/H.27-110 Kellyite (Mn,Mg,Al)3(Si,Al)2O5(OH)4 P 6₃ 6

VIII/H.27-120 Cronstedtite Fe2Fe(SiFe)O5(OH)4 P 3₁m 3m

VIII/H.27-140 Karpinskite (Mg,Ni)2Si2O5(OH)2(?) Unk Mono

VIII/H.27-150 Nepouite Ni3Si2O5(OH)4 Ccm21 mm2

VIII/H.27-160 Pecoraite Ni3Si2O5(OH)4 C 2/m 2/m

VIII/H.27-170 Brindleyite (Ni,Mg,Fe)2Al(SiAl)O5(OH)4 C 2 2

VIII/H.27-180 Maufite (Mg,Ni)Al4Si3O13·4(H2O)(?) Mono ? Mono

VIII/H.27-190 Carlosturanite (Mg,Fe,Ti,Mn)21(Si,Al)12O28(OH)34 Cm m

Other Pecoraite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Pecoraite

Ni3Si2O5(OH)4
Dana No: 71.1.2d.4 Strunz No: VIII/H.27-160
Locality:

Notes: