Piemontite Mineral Data

General Piemontite Information

Chemical Formula:

Ca2(Al,Mn,Fe)3(SiO4)3(OH) = Ca2(Mn,Fe)Al2(SiO4)(Si2O7)O(OH)

Composition:

Molecular Weight = 488.18 gm

Calcium 16.42 % Ca 22.97 % CaO

Manganese 10.13 % Mn 13.08 % MnO

Aluminum 9.95 % Al 18.80 % Al₂O₃

Iron 3.43 % Fe 4.42 % FeO

Silicon 17.26 % Si 36.92 % SiO₂

Hydrogen 0.21 % H 1.85 % H₂O

Oxygen 42.61 % O

______ ______

100.00 % 98.03 % = TOTAL OXIDE

Empirical Formula:

Ca₂Al_1.8Mn²⁺_0.9Fe²⁺_0.3(SiO₄)₃(OH)

Environment:

Contact metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1853 - Dana number changed from 58.2.1a.11

Locality:

Piedmont, Italy. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Name Pronunciation:

Piemontite + Pronunciation

Synonym:

Piedmontite

Piemontite Image

Images:

Piemontite

Comments: Red, acicular crystalline aggregates of piemontite.
Location: N'Chwaning mine, Kuruman, Nothern Cape, South Africa. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Piemontite Crystallography

Axial Ratios:

a:b:c =1.5609:1:1.7917

Cell Dimensions:

a = 8.843, b = 5.665, c = 10.15, Z = 2; beta = 115.4° V = 459.32 Den(Calc)= 3.53

Crystal System:

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

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

By Intensity(I/I_o): 2.903(1), 2.598(0.5), 4(0.5),

Crystal Structure:

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Dollase W A , American Mineralogist , 54 (1969) p.710-717, Crystal structure and cation ordering of piemontite

View Additional jPOWD Structure files for Piemontite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [2] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Piemontite

Cleavage:

{001} Good, {100} Distinct

Color:

Yellow, Carmine red, Red, Reddish brown, Reddish black.

Density:

3.4

Diaphaneity:

Translucent

Fracture:

Splintery - Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).

Habit:

Blocky - Crystal shape tends to be equant (e.g. feldspars).

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Habit:

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

Hardness:

6-7 - Orthoclase-Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

red

Optical Properties of Piemontite

Gladstone-Dale:

CI meas= -0.099 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.059 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2163,KPDmeas= 0.2246,KC= 0.2043
Ncalc = 1.69 - 1.72

Optical Data:

Biaxial (+), a=1.725-1.756, b=1.73-1.789, g=1.75-1.832, bire=0.0250-0.0760, 2V(Calc)=54-86, 2V(Meas)=50-86. Dispersion strong, r > v.

Pleochroism (x):

pale yellow, yellow, lemon yellow, orange, or red.

Pleochroism (y):

pale purple, amethyst violet, violet, rose, or deep red.

Calculated Properties of Piemontite

Electron Density:

Bulk Density (Electron Density)=3.48 gm/cc
note: Specific Gravity of Piemontite =3.53 gm/cc.

Fermion Index:

Fermion Index = 0.0092141919
Boson Index = 0.9907858081

Photoelectric:

PE_Piemontite= 6.55 barns/electron
U=PE_Piemontite x rElectron Density= 22.82 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Piemontite is Not Radioactive

Piemontite Classification

Dana Class:

58.02.01a.05 (58)Sorosilicate Insular, Mixed, Single, and Larger Tetrahedral Groups

(58.02)with cations in [6] and higher coordination; single and double groups (n=1,2)

(58.02.01a)Epidote group (Clinozoisite subgroup)

58.02.01a.01 Clinozoisite! Ca2Al3(SiO4)3(OH)=Ca2AlAl2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

58.02.01a.02 Epidote! Ca2(Fe,Al)3(SiO4)3(OH)=Ca2(Fe,Al)Al2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

58.02.01a.03 Epidote-(Pb)! (Ca,Pb,Sr)2(Al,Fe)3(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

58.02.01a.04 Mukhinite Ca2Al2V(SiO4)3(OH) P 2₁/m 2/m

58.02.01a.05 Piemontite Ca2(Al,Mn,Fe)3(SiO4)3(OH)=Ca2(Mn,Fe)Al2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

58.02.01a.06 Piemontite-(Sr)! (Ca,Mn)(Sr,Ca)Mn(Al,Mn,Fe)2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

58.02.01a.07 Manganipiemontite-(Sr)! CaSr(Mn,Fe)2Al[Si3O12](OH) P 2₁/m 2/m

58.02.01a.08 Gatelite-(Ce)! (Ca,Ce,La,Nd)4(Al,Mg,Fe)4[Si2O7][SiO4]3(O,F,OH)3 P 2₁/a 2/m

58.02.01a.09 Clinozoisite-(Sr)! CaSrAl3(Si2O7)(SiO4)O(OH) P 2₁/m 2/m

58.02.01a.10 Uedaite-(Ce)! MnCeAl2Fe(Si2O7)(SiO4)O(OH) P 2₁/m 2/m

58.02.01a.11 Epidote-(Sr)! CaSrAl2Fe(Si2O7)(SiO4)O(OH) P 2₁/m 2/m

Strunz Class:

09.BG.05a 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BG -Sorosilicates with mixed SiO4 and Si2O7 groups;

09.BG.05a Clinozoisite Ca2Al3(SiO4)3(OH)=Ca2AlAl2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

09.BG.05a Epidote Ca2(Fe,Al)3(SiO4)3(OH)=Ca2(Fe,Al)Al2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

09.BG.05a Epidote-(Pb) (Ca,Pb,Sr)2(Al,Fe)3(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

09.BG.05a Mukhinite Ca2Al2V(SiO4)3(OH) P 2₁/m 2/m

09.BG.05a Piemontite Ca2(Al,Mn,Fe)3(SiO4)3(OH)=Ca2(Mn,Fe)Al2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

09.BG.05a Piemontite-(Sr)! (Ca,Mn)(Sr,Ca)Mn(Al,Mn,Fe)2(SiO4)(Si2O7)O(OH) P 2₁/m 2/m

09.BG.05a Manganipiemontite-(Sr)! CaSr(Mn,Fe)2Al[Si3O12](OH) P 2₁/m 2/m

09.BG.05a Clinozoisite-(Sr)! CaSrAl3(Si2O7)(SiO4)O(OH) P 2₁/m 2/m

09.BG.05a Epidote-(Sr)! CaSrAl2Fe(Si2O7)(SiO4)O(OH) P 2₁/m 2/m

Other Piemontite Information

See Also:

Links to other databases for Piemontite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Dunn)
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Minerals in Thin Section-University of North Carolina
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - WWW-MINCRYST

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Print or Cut-and-Paste your Piemontite Specimen Label here :

Piemontite

Ca2(Al,Mn,Fe)3(SiO4)3(OH) = Ca2(Mn,Fe)Al2(SiO4)(Si2O7)O(OH)
Dana No: 58.02.01a.05 Strunz No: 09.BG.05a
Locality:

Notes: