Tilasite Mineral Data

General Tilasite Information

Chemical Formula:

CaMg(AsO4)F

Composition:

Molecular Weight = 222.30 gm

Calcium 18.03 % Ca 25.23 % CaO

Magnesium 10.93 % Mg 18.13 % MgO

Arsenic 33.70 % As 51.70 % As₂O₅

Oxygen 28.79 % O

Fluorine 8.55 % F 8.55 % F

- % F -3.60 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaMg(AsO₄)F

IMA Status:

Valid Species (Pre-IMA) 1895

Locality:

Langan, Varmland, Sweden. Link to MinDat.org Location Data.

Name Origin:

Named for Daniel Tilas (1712-1772), Swedish mining engineer.

Name Pronunciation:

Tilasite

Synonym:

ICSD 75618

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Tilasite Image

Images:

Tilasite

Comments: Brownish, prismatic crystals of tilasite.
Location: Cervandone, Val d'Ossola Lombardy, Italy. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Tilasite Crystallography

Axial Ratios:

a:b:c =0.8438:1:0.7486

Cell Dimensions:

a = 7.553, b = 8.951, c = 6.701, Z = 4; beta = 120.967° V = 388.46 Den(Calc)= 3.80

Crystal System:

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

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

By Intensity(I/I_o): 3.246(1), 2.682(0.9), 3.073(0.8),

Forms:

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Forms: ( 0 1 0) ( 1 3 1) ( 1 1 1) ( 1 0 0) ( 0 0 1)

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Crystal Structure:

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Bladh K W , Corbett R K , McLean W J , Laughon R B , American Mineralogist , 57 (1972) p.1880-1884, The crystal structure of tilasite

Physical Properties of Tilasite

Cleavage:

{101} Good

Color:

Violet gray, Green, Gray, Pink brown.

Density:

3.77

Diaphaneity:

Translucent

Fracture:

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

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

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

Hardness:

5 - Apatite

Luminescence:

Fluorescent, Short UV=pink-orange.

Luster:

Vitreous - Resinous

Optical Properties of Tilasite

Gladstone-Dale:

CI meas= 0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1732,KPDmeas= 0.1746,KC= 0.177
Ncalc = 1.67

Optical Data:

Biaxial (-), a=1.64, b=1.66, g=1.675, bire=0.0350, 2V(Calc)=80, 2V(Meas)=82.733. Dispersion r < v.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Tilasite

Electron Density:

Bulk Density (Electron Density)=3.60 gm/cc
note: Specific Gravity of Tilasite =3.77 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Tilasite= 25.48 barns/electron
U=PE_Tilasite x rElectron Density= 91.61 barns/cc.

Radioactivity:

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

Tilasite Classification

Dana Class:

41.05.06.01 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen

(41.05)where (A B)2 (XO4) Zq

(41.05.06)Tilasite Group

41.05.06.01 Tilasite CaMg(AsO4)F C 2/c 2/m

41.05.06.02 Isokite CaMg(PO4)F C 2/c 2/m

41.05.06.03 Panasqueiraite CaMg(PO4)(OH,F) C 2/c 2/m

Strunz Class:

08.BH.10 08 - PHOSPHATES, ARSENATES, VANADATES

08.B - Phosphates, etc. with Additional Anions, without H2O

08.BH -With medium-sized and large cations, (OH,etc.):RO4 = 1:1

08.BH.10 Durangite NaAl(AsO4)F C 2/c 2/m

08.BH.10 Isokite CaMg(PO4)F C 2/c 2/m

08.BH.10 Lacroixite NaAl(PO4)F C 2/c 2/m

08.BH.10 Maxwellite NaFe(AsO4)F Aa,A2/a Mono

08.BH.10 Panasqueiraite CaMg(PO4)(OH,F) C 2/c 2/m

08.BH.10 Tilasite CaMg(AsO4)F C 2/c 2/m

Other Tilasite Information

References:

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

See Also:

Links to other databases for Tilasite :
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 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info
16 - WWW-MINCRYST

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Ask about Tilasite here :
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Print or Cut-and-Paste your Tilasite Specimen Label here :

Tilasite

CaMg(AsO4)F
Dana No: 41.05.06.01 Strunz No: 08.BH.10
Locality:

Notes: