Gahnite Mineral Data

Gahnite Mineral Data +

General Gahnite Information

Chemical Formula:

ZnAl2O4

Composition:

Molecular Weight = 183.35 gm

Aluminum 29.43 % Al 55.61 % Al₂O₃

Zinc 35.66 % Zn 44.39 % ZnO

Oxygen 34.90 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

ZnAl₂O₄

Environment:

Metamorphic and pegmatitic rocks.

IMA Status:

Valid Species (Pre-IMA) 1807

Locality:

Falun, Sweden. Link to MinDat.org Location Data.

Name Origin:

Named after the Swedish chemist and mineralogist, J. G. Gahn (1745-1818).

Synonym:

ICSD 9559

PDF 5-669

Zinc Spinal

Gahnite Image

Images:

Gahnite

Comments: Deep blue octahedral crystals of gahnite in quartz.
Location: Franklin, Sussex County, New Jersey, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Gahnite

Comments: Optical micrograph of gahnite (blue) + Na-Ca-Li mica pseudomorph after staurolite in calcite matrix pigmented with brownish Fe-(hydr)oxide. (AmMin, 88:794).
Location: Diaspore-bearing metabauxite from East Samos (Greece). Scale: See Image.
© American Mineralogist

Gahnite Crystallography

Cell Dimensions:

a = 8.062, Z = 8; V = 524.00 Den(Calc)= 4.65

Crystal System:

Isometric - HexoctahedralH-M Symbol (4/m 3 2/m) Space Group: F d3m

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

By Intensity(I/I_o): 2.438(1), 2.861(0.84), 1.429(0.43),

Forms:

Mouse
Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize
Keyboard
S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu
Help on Above

Forms: [ 0 1 1] [ 1 1 1] [ 1 0 0]

Warning: this large pop-up is very compute intensive and may not work well with some computers.

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

Andreozzi G B , Lucchesi S , Skogby H , Della Giusta A , European Journal of Mineralogy , 13 (2001) p.391-402, Compositional dependence of cation distribution in some synthetic, (Mg,Zn)(Al,Fe)2O4 spinels, Sample: Gah1a/a

View Additional jPOWD Structure files for Gahnite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [3] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [4] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [5] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [6] [60] [61] [62] [63] [64] [65] [66] [67] [68] [69] [7] [70] [71] [72] [73] [74] [75] [76] [8] [9]

Physical Properties of Gahnite

Cleavage:

[111] Indistinct

Color:

Bluish green, Grayish green, Deep leek green, Greenish black, Bluish black.

Density:

4 - 4.6, Average = 4.3

Diaphaniety:

Subtransparent to opaque

Fracture:

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

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

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

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

8 - Topaz

Luminescence:

None.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

gray

Optical Properties of Gahnite

Gladstone-Dale:

CI meas= -0.029 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.048 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1763,KPDmeas= 0.1907,KC= 0.1852

Optical Data:

Isotropic, n=1.82.

Calculated Properties of Gahnite

Electron Density:

r_electron=4.13 gm/cc
note: r_Gahnite=4.30 gm/cc.

Fermion Index

Fermion Index = 0.01478
Boson Index = 0.98522

Photoelectric:

PE_Gahnite= 18.63 barns/electron
U=PE_Gahnite x r_electron= 76.89 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Gahnite is Not Radioactive

Gahnite Classification

Dana Class:

7.2.1.4 (7)Multiple Oxides

(7.2)(A+ B++)2 X4 Spinel group

(7.2.1)(Aluminum subgroup)

7.2.1.1 Spinel MgAl2O4 F d3m 4/m 3 2/m

7.2.1.2 Galaxite (Mn,Mg)(Al,Fe)2O4 F d3m 4/m 3 2/m

7.2.1.3 Hercynite FeAl2O4 F d3m 4/m 3 2/m

7.2.1.4 Gahnite ZnAl2O4 F d3m 4/m 3 2/m

Strunz Class:

IV/B.01-40 IV - Oxides

IV/B - Oxides with metal : oxygen = 3:4 (spinel type M3O4 and related), Aluminat-Spinels

IV/B.01 - Spinel group, Spinel - Gahnite series

IV/B.01-10 Spinel MgAl2O4 F d3m 4/m 3 2/m

IV/B.01-20 Hercynite FeAl2O4 F d3m 4/m 3 2/m

IV/B.01-30 Galaxite (Mn,Mg)(Al,Fe)2O4 F d3m 4/m 3 2/m

IV/B.01-40 Gahnite ZnAl2O4 F d3m 4/m 3 2/m

Other Gahnite Information

References:

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

Search for Gahnite using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Gahnite :
AA Mineral Specimens
A-Rocks Auction
Adams Minerals
B and L Minerals
Dakota Matrix
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Minernet.it
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Gahnite Mineral Data :

Ask about Gahnite 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 Español

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

Gahnite

ZnAl2O4
Dana No: 7.2.1.4 Strunz No: IV/B.01-40
Locality:

Notes: