Nacrite Mineral Data

Nacrite Mineral Data +

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General Nacrite Information

Chemical Formula:

Al2Si2O5(OH)4

Composition:

Molecular Weight = 258.16 gm

Aluminum 20.90 % Al 39.50 % Al₂O₃

Silicon 21.76 % Si 46.55 % SiO₂

Hydrogen 1.56 % H 13.96 % H₂O

Oxygen 55.78 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Al₂Si₂O₅(OH)₄

Environment:

May be the same as kaolinite or dickite. Hydrothermal origin.

IMA Status:

Valid Species (Pre-IMA) 1807

Locality:

Link to MinDat.org Location Data.

Name Origin:

From the French, nacre, "mother-of-pearl."

Nacrite Image

Images:

Nacrite

Comments: Colorless, transparent crystal of macrite on matrix.
Location: Hunersedge mine, Baden-Wurttemburg, Germany. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Nacrite Crystallography

Axial Ratios:

a:b:c =1.7312:1:3.0503

Cell Dimensions:

a = 8.909, b = 5.146, c = 15.697, Z = 4; beta = 113.7° V = 658.95 Den(Calc)= 2.60

Crystal System:

Monoclinic - DomaticH-M Symbol (m) Space Group: Cc

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

By Intensity(I/I_o): 7.187(1), 3.593(0.53), 4.383(0.39),

Crystal Structure:

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Zheng H , Bailey S W , Clays and Clay Minerals , 42 (1994) p.46-52, Refinement of the nacrite structure, Locality: Red Mountain near Silverton, Colorado, USA

Physical Properties of Nacrite

Cleavage:

[001] Perfect

Color:

Colorless, White, Yellowish, Brownish.

Density:

2.6

Diaphaniety:

Transparent

Fracture:

Earthy - Dull, clay-like fractures with no visible crystalline affinities, (e.g. howlite).

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Scaly - Morphology like fish scales.

Hardness:

1 - Talc

Luster:

Pearly

Streak:

white

Optical Properties of Nacrite

Gladstone-Dale:

CI meas= 0.046 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.046 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2156,KPDmeas= 0.2156,KC= 0.226

Optical Data:

Biaxial (-), a=1.557, b=1.562, g=1.563, bire=0.0060, 2V(Calc)=48, 2V(Meas)=40.

Calculated Properties of Nacrite

Electron Density:

r_electron=2.62 gm/cc
note: r_Nacrite=2.60 gm/cc.

Fermion Index

Fermion Index = 0.01043
Boson Index = 0.98957

Photoelectric:

PE_Nacrite= 1.48 barns/electron
U=PE_Nacrite x r_electron= 3.87 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Nacrite is Not Radioactive

Nacrite Classification

Dana Class:

71.1.1.3 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.1)with 1:1 layers

(71.1.1)Kaolinite group

71.1.1.1 Dickite Al2Si2O5(OH)4 Cc m

71.1.1.2 Kaolinite Al2Si2O5(OH)4 P1 1

71.1.1.3 Nacrite Al2Si2O5(OH)4 Cc m

71.1.1.4 Halloysite Al2Si2O5(OH)4 Cc m

71.1.1.4a Endellite? Al2Si2O5(OH)4·2(H2O) Cc m

71.1.1.5 Odinite (Fe,Mg,Al,Fe,Ti,Mn)2.5(Si,Al)2O5(OH)4 Cm m

Strunz Class:

VIII/H.25-30 VIII - Silicates

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

VIII/H.25 - Kaolinite group

VIII/H.25-10 Kaolinite Al2Si2O5(OH)4 P1 1

VIII/H.25-20 Dickite Al2Si2O5(OH)4 Cc m

VIII/H.25-30 Nacrite Al2Si2O5(OH)4 Cc m

VIII/H.25-40 Halloysite Al2Si2O5(OH)4 Cc m

Other Nacrite 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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Nacrite

Al2Si2O5(OH)4
Dana No: 71.1.1.3 Strunz No: VIII/H.25-30
Locality:

Notes: