Scawtite Mineral Data

General Scawtite Information

Chemical Formula:

Ca7Si6(CO3)O18•2(H2O)

Composition:

Molecular Weight = 833.09 gm

Calcium 33.68 % Ca 47.12 % CaO

Silicon 20.23 % Si 43.27 % SiO₂

Hydrogen 0.48 % H 4.32 % H₂O

Carbon 1.44 % C 5.28 % CO₂

Oxygen 44.17 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₇Si₆(CO₃)O₁₈•2(H₂O)

Environment:

Rare constituent of hybrid rocks formed by the assimilation of limestone by dolerite.

IMA Status:

Valid Species (Pre-IMA) 1929

Locality:

Scawt Hill, Antrim, Ireland. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Name Pronunciation:

Scawtite

Synonym:

ICSD 73333

PDF 31-361

Scawtite Image

Images:

Scawtite

Comments: 1 to 2 mm transparent crystals of Scawtite on dark matrix (see pink arrows in photo).
Location: Scawt Hill, Antrim, Ireland. Scale: Picture size 5 mm.
© John Veevaert

Scawtite Crystallography

Axial Ratios:

a:b:c =0.6667:1:0.4362

Cell Dimensions:

a = 10.121, b = 15.18, c = 6.623, Z = 2; beta = 100.55° V = 1,000.34 Den(Calc)= 2.77

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 3.02(1), 2.991(0.8), 3.204(0.55),

Physical Properties of Scawtite

Cleavage:

{001} Perfect, {010} Poor

Color:

Colorless.

Density:

2.77

Diaphaneity:

Transparent

Habit:

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

Hardness:

4-5 - Fluorite-Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Scawtite

Gladstone-Dale:

CI meas= -0.023 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.023 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2199,KPDmeas= 0.2199,KC= 0.2148
Ncalc = 1.6

Optical Data:

Biaxial (+), a=1.597-1.603, b=1.606-1.609, g=1.618-1.621, bire=0.0180-0.0210, 2V(Calc)=72-84, 2V(Meas)=74-78.

Calculated Properties of Scawtite

Electron Density:

Bulk Density (Electron Density)=2.78 gm/cc
note: Specific Gravity of Scawtite =2.77 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Scawtite= 4.91 barns/electron
U=PE_Scawtite x rElectron Density= 13.65 barns/cc.

Radioactivity:

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

Scawtite Classification

Dana Class:

64.02.01.01 (64)Cyclosilicates

(64.02)3-membered rings with other anion groups

(64.02.01)Dana Group

64.02.01.01 Scawtite Ca7Si6(CO3)O18•2(H2O) C 2/m 2/m

Strunz Class:

09.CK.15 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CK -[Si6O18]12- 6-membered single rings, with insular complex anions

09.CK.15 Scawtite Ca7Si6(CO3)O18•2(H2O) C 2/m 2/m

Other Scawtite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

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

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

Scawtite

Ca7Si6(CO3)O18•2(H2O)
Dana No: 64.02.01.01 Strunz No: 09.CK.15
Locality:

Notes:

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