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Legrandite
Current inventory:  1 gem
 

Chemistry:  Zn₂(AsO₄)(OH)·(H₂O)

Discovered in 1932 ;   IMA status: Valid (pre-IMA; Grandfathered).
Legrandite is named in honor of a Mr. Legrand, Belgian mine manager, who collected the first specimen.

Classification

Mineral Classification:

Phosphates

Strunz 10th Ed. ID:

8.DC.10

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H₂O
C : With only medium-sized cations, (OH, etc.):RO₄ = 1:1 and < 2:1

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As prismatic crystals, elongated, to 28 cm, striated; typically in sprays or sheaflike aggregates.

Twinning:

None

Physical Properties

Cleavage:

[100] Fair to Poor, Imperfect

Fracture:

Uneven

Tenacity:

Brittle

Hardness (Mohs):

4.5

Density:

3.98 - 4.01 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Colorless, pale to bright Yellow, Yellowish Orange

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.675 - 1.740  Biaxial ( + )

Birefringence:

0.0600

Dispersion:

Distinct; r < v

Pleochroism:

X = Y = colorless to yellow; Z = yellow

Occurances

Geological Setting:

An uncommon secondary mineral in the oxidized zone of Zn–As-bearing deposits; rare in granite pegmatite.

Type Locality:

Flor de Peña Mine, Lampazos de Naranjo (Lampazos), Mun. de Lampazos de Naranjo, Nuevo Leon, Mexico

Year Discovered:

1932

View mineral photos:

Legrandite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Legrandite is a very rare phosphate mineral that is found in shades of yellow and is rarely faceted as most specimens are kept by mineral collectors. The very few gems to be found are usually very small and included but are very beautiful due to the bright yellow color.

The two most notable occurances of Legrandite are from Mexico at the Ojuela mine, Mapimí, Durango, and the Flor de Peña Mine, Lampazos de Naranjo, Nuevo Leon. These two locations produce the finest crystals in the world. Other minor locations are Boa Vista, near Galiléia, Minas Gerais, Brazil; Ogibira mine, near Osa, Okayama Prefecture, Japan; Tsumeb, Namibia; Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA
 

  
Legrandite gems for sale: