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Gormanite
Current inventory:  0 gems
 

Gormanite

  
Gormanite was named in 1981 by B. Darko Sturman, Joseph A. Mandarino, Mary E. Mrose and P. J. Dunn to honor Donald Herbert Gorman (1922 ), exploration mineralogist and Professor of Mineralogy of the University of Toronto, Canada.

Discovered in 1977;   IMA status:  Valid (IMA approved 1981)

 

Chemistry

 

 

Chemical Formula:

Fe2+3Al4(PO4)4(OH)62(H2O)

 

Hydrated Iron Aluminum Phosphate Hydroxide

Molecular Weight:

793.43 gm

Composition:

Aluminum

13.60 %

Al

25.70 %

Al2O3

 

Iron

21.12 %

Fe

27.17 %

FeO

 

Phosphorus

15.62 %

P

35.78 %

P2O5

 

Hydrogen

1.27 %

H

11.35 %

H2O

 

Oxygen

48.40 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Phosphate

Strunz 8th Ed. ID:

7/D.11-100

Nickel-Strunz 10th Ed. ID:

8.DC.45

 

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H
2O
C : With only medium-sized cations, (OH, etc.):RO
4 = 1:1 and < 2:1

Related to:

Gormanite-Souzalite Series. Isostructural with Souzalite. The Fe2+ analogue of Souzalite.

Varieties:

None

Synonyms:

IMA 1977-030

 

 

Crystal Data

   

   

Crystallography:

Triclinic - Unknown or Uncertain Class

Crystal Habit:

Crystals are elongated along [010], with large {001}, giving a bladelike aspect, with smaller {100}, {102}, {102}, {010}, to 1 cm; commonly in radial aggregates.

Twinning:

Polysynthetic around [010], composition plane {001}, universal.

 

 

Physical Properties

   

 

Cleavage:

Poor/Indistinct on {001}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

4.0 - 5.0

Density:

3.10 - 3.13 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Blue-Green

Transparency:

Semi-Transparent to Opaque

Luster:

Vitreous

Refractive Index:

1.619 - 1.660  Biaxial  ( - )

Birefringence:

0.0410

Dispersion:

Strong to Very Strong; r < v or r > v

Pleochroism:

X = Z = colorless; Y = blue

 

 

Occurances

   

   

Geological Setting:

As low-temperature fracture fillings in phosphate-ironstones (Yukon Territory, Canada); in fractures in tonalite (Bisbee, Arizona, USA).

Common Associations:

Souzalite, Siderite, Ludlamite, Oxidized Vivianite, Arrojadite, Kryzhanovskite, Quartz (Yukon Territory, Canada); Chlorite, Calcite, Quartz (Bisbee, Arizona, USA).

Common Impurities:

None

Co-Type Locality:

Big Fish River, Dawson Mining District, Yukon Territory, Canada;
Rapid Creek, Dawson Mining District, Yukon Territory, Canada

Year Discovered:

1977; IMA approved 1981

View mineral photos:

Gormanite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org 
Webmineral.com

 

 


Gormanite is one of the new phosphate minerals being found from the hydrothermal phosphate deposits at the Rapid Creek, Big Fish River and Blow River areas in the Yukon Territory of Canada. Iron-rich Gormanite forms a series with Magnesium-rich Souzalite. Gormanite is a relatively new mineral having been discovered in 1977 and is somewhat rare. It forms attractive, colorful well formed crystals.

Gormanite is found at only a few localities; from Rapid Creek, Yukon Territory, Canada. In the USA, in large crystals at Bisbee, Cochise County, Arizona; in New Hampshire, from the G.E. Smith mine, Newport, Sullivan County and the Charles Davis pegmatite, Groton, Grafton County At the Tsaobismund pegmatite, 60 km south of Karibib, Namibia.
 

  
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