Graftonite
Current inventory:  0 gems
 

  
Graftonite was named by Samuel L. Penfield in 1900 for the type locality on Melvin Mountain, Grafton, Grafton County, New Hampshire, USA.

Discovered in 1900; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Fe²⁺,Mn²⁺,Ca)₃(PO₄)₂

Iron Manganese Phosphate

Molecular Weight:

351.93 gm

Composition:

Calcium

3.42 %

Ca

4.78 %

CaO

Manganese

14.05 %

Mn

18.14 %

MnO

Iron

28.56 %

Fe

36.75 %

FeO

Phosphorus

17.60 %

P

40.33 %

P₂O₅

Oxygen

36.37 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/A.04-20

Nickel-Strunz 10th Ed. ID:

8.AB.20

8 : PHOSPHATES, ARSENATES, VANADATES
A : Phosphates, etc. without additional anions, without H₂O
B : With medium-sized cations

Related to:

None

Varieties:

None

Synonyms:

Repossite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Very rare crude crystals, stout prismatic; usually massive, cleavable, in laminated intergrowths with Triphylite, to 0.5 m.

Twinning:

None

Physical Properties

Cleavage:

Good on {010}, Fair on {100}

Fracture:

Irregular/Uneven to Subconchoidal

Tenacity:

Brittle

Moh's Hardness:

5.0

Density:

3.67 - 3.79 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Readily soluble in acids.

Optical Properties

Color:

Salmon-pink to reddish brown, dark brown when altered; nearly colorless in transmitted light.

Transparency:

Transparent to Translucent

Luster:

Vitreous towards Resinous

Refractive Index:

1.695 - 1.736  Biaxial ( + ) 

Birefringence:

0.024 - 0.027

Dispersion:

Relatively weak; r > v  or  r < v

Pleochroism:

Faint; X = Y = colorless; Z = pink

Occurances

Geological Setting:

A primary mineral or exsolution product in complex granite pegmatites.

Common Associations:

Triphylite, Lithiophilite, Sarcopside, Ferrisicklerite, Heterosite, Arrojadite, Fairfieldite, Barbosalite, Huréaulite, Almandine, Zircon, Albite, Muscovite, Biotite

Common Impurities:

None

Type Locality:

Melvin Mountain, Grafton, Grafton Co., New Hampshire, USA

Year Discovered:

1900

View mineral photos:

Graftonite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Graftonite is a primary phosphate mineral found in complex granitic pegmatites and often found associated with Triphylite. Its color is a salmon-pink to reddish brown to dark brown when altered. It is not a particularily attractive gem so mostly one for collectors of rare and unusual gems.

Distribution: In the USA, on Melvin Mountain (Type Locality), about eight km west of Grafton, at the Palermo #1 and Rice mines, near North Groton, Grafton County, at the Parker Mountain quarry, Center Strafford, Strafford County, and many other places in New Hampshire; from the Waisenen quarry, Greenwood, Oxford County, Maine; in the Bull Moose mine, five km southeast of Custer, Custer County, and at the Nickel Plate mine, 1.5 km south of Keystone, Pennington County, South Dakota. From near São Luiz do Paraitinga, São Paulo, and the Énio pegmatite mine, northeast of Galiléia, Minas Gerais, Brazil. At the Ranquel and Cacique Canchuleta mines, San Luis, Argentina. From Sidi Bou Othmane, Morocco. In the Valle della Madonna, Brissago, Tessin, Switzerland. At Olgiasca, Lake Como, Lombardy, Italy. From Hagendorf, Bavaria, Germany. In the Kondakov district, eastern Siberia, Russia. Additional localities continue to be recognized.
 

  
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