Gobbinsite Mineral Data

General Gobbinsite Information

Chemical Formula:

(Na2,Ca)2K2Al6Si10O32•12(H2O)

Composition:

Molecular Weight = 1,339.93 gm

Potassium 6.13 % K 7.38 % K₂O

Sodium 4.29 % Na 5.78 % Na₂O

Calcium 1.79 % Ca 2.51 % CaO

Aluminum 12.48 % Al 23.59 % Al₂O₃

Silicon 20.96 % Si 44.84 % SiO₂

Hydrogen 1.81 % H 16.13 % H₂O

Oxygen 52.54 % O

______ ______

100.00 % 100.24 % = TOTAL OXIDE

Empirical Formula:

Na_2.5Ca_0.6K_2.1Al_6.2Si₁₀O₃₂•12(H₂O)

Environment:

Formed from sodium rich fluids, in basalts and related igneous rocks.

IMA Status:

Approved IMA 1982

Locality:

Basalt cliffs near Hills Port, south of the Gobbins area, County Antrim, Northern Ireland. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Name Pronunciation:

Gobbinsite + Pronunciation

Synonym:

ICSD 30975

PDF 35-559

Gobbinsite Image

Images:

Gobbinsite

Comments: White opaque crystalline gobbinsite in vug.
Location: Island Magee, County, Antrim, Northern Ireland. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Gobbinsite Crystallography

Axial Ratios:

a:b:c =1.0307:1:1.0374

Cell Dimensions:

a = 10.1027, b = 9.8016, c = 10.1682, Z = 1; V = 1,006.88 Den(Calc)= 2.21

Crystal System:

Orthorhombic - Pyramidal H-M Symbol (mm2) Space Group: P mn2₁

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

By Intensity(I/I_o): 3.201(1), 4.116(1), 7.11(1),

Physical Properties of Gobbinsite

Cleavage:

None

Color:

Lemon white, Chalky white, Light brown.

Density:

2.147

Diaphaneity:

Transparent to Translucent

Fracture:

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

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Lath - Shaped like a small, thin plaster lath, tabular (rectangular) in shape.

Hardness:

4 - Fluorite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Gobbinsite

Gladstone-Dale:

CI meas= -0.004 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.025 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.222,KPDmeas= 0.2285,KC= 0.2277
Ncalc = 1.49 - 1.5

Optical Data:

Biaxial (-), a=1.489, b=1.489, g=1.494, bire=0.0050, 2V(Calc)=0, 2V(Meas)=0.

Calculated Properties of Gobbinsite

Electron Density:

Bulk Density (Electron Density)=2.17 gm/cc
note: Specific Gravity of Gobbinsite =2.15 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Gobbinsite= 2.09 barns/electron
U=PE_Gobbinsite x r_electron= 4.53 barns/cc.

Radioactivity:

GRapi = 89.22 (Gamma Ray American Petroleum Institute Units)
Concentration of Gobbinsite per GRapi unit = 1.12 (%)

Estimated Radioactivity from Gobbinsite - barely detectable

Gobbinsite Classification

Dana Class:

77.01.03.04 (77)Tectosilicate Zeolite group

(77.01)true zeolites

(77.01.03)Gismondine and related species

77.01.03.01 Gismondine Ca2Al4Si4O16•9(H2O) P 2₁/c 2/m

77.01.03.02 Amicite K2Na2Al4Si4O16•5(H2O) I2 2

77.01.03.03 Garronite Na2Ca5Al12Si20O64•27(H2O) I 4₁/a 4/m

77.01.03.04 Gobbinsite (Na2,Ca)2K2Al6Si10O32•12(H2O) P mn2₁ mm2

77.01.03.05 Harmotome (Ba,Na,K)1-2(Si,Al)8O16•6(H2O) P 2₁/m 2/m

77.01.03.06 Phillipsite-Na (Na,K,Ca)1-2(Si,Al)8O16•6(H2O) P 2₁/m 2/m

77.01.03.06a Phillipsite-Ca! (Ca,K,Na)1-2(Si,Al)8O16•6(H2O) P 2₁/m 2/m

77.01.03.06b Phillipsite-K! (K,Na,Ca)1-2(Si,Al)8O16•6(H2O) P 2₁/m 2/m

77.01.03.08 Perlialite K8Tl4Al12Si24O72•20(H2O) P 6/mmm 6/m 2/m 2/m

77.01.03.09 Paulingite-K (K2,Ca,Na2,Ba)5Al10Si35O90•45(H2O) Im3m 4/m 3 2/m

77.01.03.09a Paulingite-Na! (Na2,K2,Ca,Ba)5Al10Si35O90•45(H2O) Im3m 4/m 3 2/m

77.01.03.09b Paulingite-Ca! (Ca,K,Na,Ba)5[Al10Si35O84]•34(H2O) Im3m 4/m 3 2/m

77.01.03.10 Mazzite-Mg K2CaMg2(Al,Si)36O72•28(H2O) P 6₃/mmc 6/m 2/m 2/m

77.01.03.10a Mazzite-Na! Na8Al8Si28O72•30H2O P 6₃/mmc 6/m 2/m 2/m

77.01.03.11 Merlinoite (K,Ca,Na,Ba)7Si23Al9O64•23(H2O) I mmm 2/m 2/m 2/m

77.01.03.12 Montesommaite (K,Na)9Al9Si23O64•10(H2O) F dd2 mm2

Strunz Class:

09.GC.05 09 - SILICATES (Germanates)

09.G - Tektosilicates with Zeolitic H2O

09.GC -Chains of doubly-connected 4-membered rings

09.GC.05 Amicite K2Na2Al4Si4O16•5(H2O) I2 2

09.GC.05 Garronite Na2Ca5Al12Si20O64•27(H2O) I 4₁/a 4/m

09.GC.05 Gobbinsite (Na2,Ca)2K2Al6Si10O32•12(H2O) P mn2₁ mm2

09.GC.05 Gismondine Ca2Al4Si4O16•9(H2O) P 2₁/c 2/m

Other Gobbinsite Information

References:

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

See Also:

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

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Gobbinsite

(Na2,Ca)2K2Al6Si10O32•12(H2O)
Dana No: 77.01.03.04 Strunz No: 09.GC.05
Locality:

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