Tuscanite Mineral Data

Tuscanite Mineral Data +

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General Tuscanite Information

Chemical Formula:

K(Ca,Na)6(Si,Al)10O22(SO4,CO3,(OH)2)·(H2O)

Composition:

Molecular Weight = 1,101.39 gm

Potassium 3.19 % K 3.85 % K₂O

Sodium 1.04 % Na 1.41 % Na₂O

Calcium 19.29 % Ca 26.99 % CaO

Magnesium 0.22 % Mg 0.37 % MgO

Aluminum 9.06 % Al 17.13 % Al₂O₃

Iron 0.51 % Fe 0.65 % FeO

Silicon 16.07 % Si 34.37 % SiO₂

Hydrogen 0.27 % H 2.45 % H₂O

Carbon 0.65 % C 2.40 % CO₂

Sulfur 4.08 % S 10.18 % SO₃

Oxygen 45.61 % O

______ ______

100.00 % 99.78 % = TOTAL OXIDE

Empirical Formula:

K_0.9Ca_5.3Na_0.5Mg_0.1Fe²⁺_0.1Si_6.3Al_3.7O₂₂(SO₄)_1.4(CO₃)_0.6(OH)·(H₂O)

Environment:

Within ejected blocks of metasomatized carbonate rocks in a pumice deposit.

IMA Status:

Approved IMA 1977

Locality:

Latera caldera, Pitigliano, near Grosseto, Tuscan, and at Sacrofano, Lazio, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for the Tuscany region of Italy where the mineral was first found.

Synonym:

ICSD 9683

PDF 29-1035

Tuscanite Image

Images:

Tuscanite Augite

Comments: Translucent tuscanite microcrystal in in vug in low-Fe augite (var. fassaite).
Location: Pitigliano Quarry, Grosseto, Tuscany, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Tuscanite Crystallography

Axial Ratios:

a:b:c =4.7037:1:2.1307

Cell Dimensions:

a = 24.036, b = 5.11, c = 10.888, Z = 2; beta = 106.95° V = 1,279.21 Den(Calc)= 2.86

Crystal System:

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

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

By Intensity(I/I_o): 2.872(1), 11.51(1), 3.065(0.47),

Crystal Structure:

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Mellini M , Merlino S , Rossi G , American Mineralogist , 62 (1977) p.1114-1120, The crystal structure of tuscanite, Note Sample from the pumice deposit in Pitigliano, Tuscany, Italy

Physical Properties of Tuscanite

Cleavage:

[100] Distinct

Color:

Colorless.

Density:

2.83

Diaphaniety:

Transparent

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Tuscanite

Gladstone-Dale:

CI meas= -0.002 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2054,KPDmeas= 0.2075,KC= 0.2072

Optical Data:

Biaxial (-), a=1.581, b=1.59, g=1.591, bire=0.0100, 2V(Calc)=36, 2V(Meas)=40.

Calculated Properties of Tuscanite

Electron Density:

r_electron=2.82 gm/cc
note: r_Tuscanite=2.83 gm/cc.

Fermion Index

Fermion Index = 0.00869
Boson Index = 0.99131

Photoelectric:

PE_Tuscanite= 4.00 barns/electron
U=PE_Tuscanite x r_electron= 11.27 barns/cc.

Radioactivity:

GRapi = 45.95 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Tuscanite - barely detectable

Tuscanite Classification

Dana Class:

73.1.2.2 (73)Phyllosilicate Condensed Tetrahedral Sheets

(73.1)with double layers

(73.1.2)Latiumite group

73.1.2.1 Latiumite (Ca,K)8(Al,Mg,Fe)(Si,Al)10O25(SO4) P 2₁ 2

73.1.2.2 Tuscanite K(Ca,Na)6(Si,Al)10O22(SO4,CO3,(OH)2)·(H2O) P 2₁/a 2/m

Strunz Class:

VIII/H.06-20 VIII - Silicates

VIII/H - Phyllosilicates (layered), Tetragonal or pseudotetragonal layered structures [Si4O10]4- and others

VIII/H.06 - Latiumite - Tuscanite series

VIII/H.06-10 Latiumite (Ca,K)8(Al,Mg,Fe)(Si,Al)10O25(SO4) P 2₁ 2

VIII/H.06-20 Tuscanite K(Ca,Na)6(Si,Al)10O22(SO4,CO3,(OH)2)·(H2O) P 2₁/a 2/m

Other Tuscanite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Tuscanite

K(Ca,Na)6(Si,Al)10O22(SO4,CO3,(OH)2)·(H2O)
Dana No: 73.1.2.2 Strunz No: VIII/H.06-20
Locality:

Notes: