Tumchaite Mineral Data

General Tumchaite Information

Chemical Formula:

Na2(Zr,Sn)Si4O11•2(H2O)

Composition:

Molecular Weight = 462.51 gm

Sodium 9.94 % Na 13.40 % Na₂O

Zirconium 14.79 % Zr 19.98 % ZrO₂

Silicon 24.29 % Si 51.96 % SiO₂

Tin 5.13 % Sn 6.52 % SnO₂

Hydrogen 0.87 % H 7.79 % H₂O

Oxygen 44.97 % O

______ ______

100.00 % 99.65 % = TOTAL OXIDE

Empirical Formula:

Na₂Zr_0.75Sn_0.2Si₄O₁₁•2(H₂O)

Environment:

From a core sample of rocks formed by the hydrothermal alteration of dolomite-calcite carbonatites. Zr-analogue of penkvilksite-1M

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Vuoriyarvi alkali-ultrabasic massif, North Karelia on the north shore of the Vuoriyarvi lake, Murmansk Region, Russia. Link to MinDat.org Location Data.

Name Origin:

The mineral is named for the river Tumcha near Vuoriyarvi massif.

Synonym:

ICSD 89740

IMA1999-041

Tumchaite Image

Images:

Tumchaite

Comments: SEM photomicrograph of typical tumchaite crystals shaped by the prism {hkl}, and by two pinacoids {100} and {h0l}. Grains are tabular on (100), elongated along [001]. (AmMin 85:1517).
Location: Vuoriyarvi alkali-ultrabasic massif, Murmansk Region, Russia. Scale: See Image.
© American Mineralogist

Tumchaite Crystallography

Axial Ratios:

a:b:c =1.0369:1:0.8547

Cell Dimensions:

a = 9.144, b = 8.818, c = 7.537, Z = 2; beta = 113.22° V = 558.49 Den(Calc)= 2.75

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 8.4(1)(100), 2.691(0.9)(131), 2.902(0.9)(211),3.401(0.9)(202), 5.38(0.9)(111), 4(0.8)(111), 2.19(0.7)(313,41

Physical Properties of Tumchaite

Cleavage:

{100} Perfect

Color:

Colorless.

Density:

2.78

Diaphaneity:

Translucent to transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

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

Habit:

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

Hardness:

4.5 - Between Fluorite and Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Tumchaite

Gladstone-Dale:

CI meas= 0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.004 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2124,KPDmeas= 0.2101,KC= 0.2115
Ncalc = 1.58 - 1.59

Optical Data:

Biaxial (-), a=1.57, b=1.588, g=1.594, bire=0.0240

Calculated Properties of Tumchaite

Electron Density:

Bulk Density (Electron Density)=2.69 gm/cc
note: Specific Gravity of Tumchaite =2.75 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Tumchaite= 35.05 barns/electron
U=PE_Tumchaite x rElectron Density= 94.21 barns/cc.

Radioactivity:

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

Tumchaite Classification

Dana Class:

70.02.02.02 (70)Inosilicate Column or Tube Structures

(70.02)with Si2O7 dimers

(70.02.02)Dana Group

70.02.02.01 Penkvilksite Na4(Ti,Zr)2[Si8O22]•4(H2O) P 2₁/c 2/m

70.02.02.02 Tumchaite! Na2(Zr,Sn)Si4O11•2(H2O) P 2₁/c 2/m

Strunz Class:

09.EA.60 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EA -Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings

09.EA.60 Penkvilksite Na4(Ti,Zr)2[Si8O22]•4(H2O) P 2₁/c 2/m

09.EA.60 Tumchaite! Na2(Zr,Sn)Si4O11•2(H2O) P 2₁/c 2/m

Other Tumchaite Information

References:

NAME( AmMin, v 85, p 1516) PHYS. PROP.(AmMin, v 85, p 1516) OPTIC PROP.(AmMin, v 85, p 1516)

See Also:

Links to other databases for Tumchaite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info
13 - WWW-MINCRYST

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Tumchaite

Na2(Zr,Sn)Si4O11•2(H2O)
Dana No: 70.02.02.02 Strunz No: 09.EA.60
Locality:

Notes:

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