Gehlenite Mineral Data (original) (raw)

General Gehlenite Information

Chemical Formula:

Ca2Al(AlSi)O7

Composition:

Molecular Weight = 274.20 gm

Calcium 29.23 % Ca 40.90 % CaO

Aluminum 19.68 % Al 37.18 % Al2O3

Silicon 10.24 % Si 21.91 % SiO2

Oxygen 40.84 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca2Al2SiO7

Environment:

Contact metamorphic mineral in limestone.

IMA Status:

Valid Species (Pre-IMA) 1815

Locality:

Trentino, Italy. Link to MinDat.org Location Data.

Name Origin:

Named after the German chemist, A. F. Gehlen (1775-1815).

Name Pronunciation:

Gehlenite + Pronunciation

Synonym:

ICSD 39921

PDF 35-755

Gehlenite Image

Images:

	Gehlenite Comments: Contact area between vesuvianite (right) and gehlenite (left). Note the lamellae of clintonite included mainly in the gehlenite crystals (CanMin v. 41. p 1259). Location: Skarns along the contact of a diorite intrusion at Oravit¸a, Banat, in Romania.Scale: Image size 2.7 mm. © Canadian Mineralogist

Gehlenite Crystallography

Axial Ratios:

a:c = 1:0.6589

Cell Dimensions:

a = 7.69, c = 5.067, Z = 2; V = 299.64 Den(Calc)= 3.04

Crystal System:

Tetragonal - ScalenohedralH-M Symbol (4 2m) Space Group: P 421m

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

By Intensity(I/Io): 1.75(1), 2.85(1), 2.43(0.7),

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

| | Louisnathan S J , The Canadian Mineralogist , 10 (1971) p.822-837, Refinement of the crystal structure of a natural gehlenite, Ca2Al(Al,Si)2O7 View Additional jPOWD Structure files for Gehlenite [1] [2] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Physical Properties of Gehlenite

Cleavage:

{001} Good

Color:

Brown, Colorless, Greenish, Gray, Yellow.

Density:

2.9 - 3.07, Average = 2.98

Diaphaneity:

Transparent to translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

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

Habit:

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

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

5-6 - Between Apatite and Orthoclase

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Gehlenite

Gladstone-Dale:

CI meas= -0.069 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.049 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2188,KPDmeas= 0.2228,KC= 0.2084
Ncalc = 1.6 - 1.64

Optical Data:

Uniaxial (-), e=1.66, w=1.67, bire=0.0100.

Calculated Properties of Gehlenite

Electron Density:

Bulk Density (Electron Density)=3.02 gm/cc
note: Specific Gravity of Gehlenite =3.04 gm/cc.

Fermion Index:

Fermion Index = 0.0053740313
Boson Index = 0.9946259687

Photoelectric:

PEGehlenite = 4.57 barns/electron
U=PEGehlenite x rElectron Density= 13.77 barns/cc.

Radioactivity:

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

Gehlenite Classification

Dana Class:

55.04.01.02 (55)Sorosilicate Si2O7 Groups, Generally with No Additional Anions

(55.04)with cations in [8] and lower coordination

(55.04.01)Melilite group

55.04.01.01 Akermanite Ca2MgSi2O7 P 421m 4 2m

55.04.01.02 Gehlenite Ca2Al(AlSi)O7 P 421m 4 2m

55.04.01.03 Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 421m 4 2m

55.04.01.04 Okayamalite! Ca2B2SiO7 P 421m 4 2m

55.04.01.05 Alumoakermanite! (Ca,Na)2(Al,Mg,Fe)(Si2O7) P 421m 4 2m

Strunz Class:

09.BB.10 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BB -Si2O7 groups, without non-tetrahedral anions;

09.BB.10 Akermanite Ca2MgSi2O7 P 421m 4 2m

09.BB.10 Cebollite Ca5Al2(SiO4)3(OH)4 Unk Ortho

09.BB.10 Gugiaite Ca2BeSi2O7 P 421m 4 2m

09.BB.10 Gehlenite Ca2Al(AlSi)O7 P 421m 4 2m

09.BB.10 Jeffreyite (Ca,Na)2(Be,Al)Si2(O,OH)7 C 2221 2 2 2

09.BB.10 Hardystonite Ca2ZnSi2O7 P 421m 4 2m

09.BB.10 Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 421m 4 2m

09.BB.10 Okayamalite! Ca2B2SiO7 P 421m 4 2m

Other Gehlenite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

Search for Gehlenite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Gehlenite :

A Bijoux Google Search for Gehlenite
Adam's Minerals Google Search for Gehlenite
Cape Minerals Google Search for Gehlenite
Dakota Matrix Minerals Google Search for Gehlenite
Excalibur Mineral Corp. Google Search for Gehlenite
Exceptional Minerals Google Search for Gehlenite
John Betts Fine Minerals Search for Gehlenite
McDougall Minerals Google Search for Gehlenite
Mineral News Website Link
Rock and Mineral Shows Google Search for Gehlenite
Weinrich Minerals, Inc. Google Search for Gehlenite

Ask about Gehlenite 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 Espa�ol

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

Gehlenite

Ca2Al(AlSi)O7
Dana No: 55.04.01.02 Strunz No: 09.BB.10
Locality:

Notes: