Tilasite Mineral Data

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.

Synonym:

ICSD 75618

PDF 2-485

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:

Mouse
Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize
Keyboard
S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu
Help on Above

Forms: [ 0 1 0] [ 1 3 1] [ 1 1 1] [ 1 0 0] [ 0 0 1]

Warning: this large pop-up is very compute intensive and may not work well with some computers.

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

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

Diaphaniety:

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.

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

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:

r_electron=3.60 gm/cc
note: r_Tilasite=3.77 gm/cc.

Fermion Index

Fermion Index = 0.01131
Boson Index = 0.98869

Photoelectric:

PE_Tilasite= 25.48 barns/electron
U=PE_Tilasite x r_electron= 91.61 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Tilasite is Not Radioactive

Tilasite Classification

Dana Class:

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

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

(41.5.6)Tilasite Group

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

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

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

Strunz Class:

VII/B.25-30 VII - Phosphates, Arsenates and Vanadates

VII/B - Waterfree phosphates with unfamiliar anions F, Cl, O, OH. cations of medium and big size: Mg, Cu, Zn, and Ca, Na, K, Ba, Pb

VII/B.25 - Isokite - Thadeuite series

VII/B.25-10 Isokite CaMg(PO4)F C 2/c 2/m

VII/B.25-20 Panasqueiraite CaMg(PO4)(OH,F) C 2/c 2/m

VII/B.25-30 Tilasite CaMg(AsO4)F C 2/c 2/m

VII/B.25-40 Lacroixite NaAl(PO4)F C 2/c 2/m

VII/B.25-50 Durangite NaAl(AsO4)F C 2/c 2/m

VII/B.25-55 Maxwellite NaFe(AsO4)F Aa,A2/a Mono

VII/B.25-60 Nacaphite Na(Na,Ca)2(PO4)F P1 1

VII/B.25-70 Spodiosite? Ca2(PO4)F Pbcm 2/m 2/m 2/m

VII/B.25-80 Thadeuite (Ca,Mn)(Mg,Fe,Mn)3(PO4)2(OH,F)2 C 222₁ 2 2 2

Other Tilasite Information

References:

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

Search for Tilasite using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Tilasite :
AA Mineral Specimens
B and L Minerals
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Minernet.it
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Tilasite Mineral Data :

Ask about Tilasite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Tilasite

CaMg(AsO4)F
Dana No: 41.5.6.1 Strunz No: VII/B.25-30
Locality:

Notes: