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Periclase
Current inventory:  0 gems
 

Periclase

  
Periclase is named f
rom the Greek words "peri" and "klastos" meaning "to break around", in allusion to the perfect cubic cleavage.

Discovered in 1840;   IMA status: Valid (pre-IMA; Grandfathered).

 

Chemistry

 

 

Chemical Formula:

MgO

 

Magnesium Oxide

Molecular Weight:

40.30 gm

Composition: 

Magnesium

60.30 %

Mg

100.00 %

MgO

Oxygen

39.70 %

O

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/A.04-10

Nickel-Strunz 10th Ed. ID:

4.AB.25

 

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
A : Metal: Oxygen = 2:1 and 1:1
B : M:O = 1:1 (and up to 1:1.25); with small to medium-sized cations only

Related to:

Periclase Group. Periclase - Murdochite Series. Isostructural with Halite.

Varieties:

Ferropericlase, Lavernite

Synonyms:

Periclasa, Periclasia, Periclasite

 

 

Crystal Data

   

   

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

As small octahedra, less commonly cubo-octahedra or dodecahedra, may be clustered; granular, massive.

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

[001] Perfect, [111] Imperfect; may exhibit parting on [011]

Fracture:

Irregular/Uneven, Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5

Density:

3.56 - 3.68 (g/cm3)

Luminescence:

Light Yellow under LW UV

Radioactivity:

Not Radioactive

Other:

Slightly soluble in water when powdered, to give an alkaline reaction

 

 

Optical Properties

   

   

Color:

Colorless, Grayish White, Yellow, Brownish Yellow; may be Green or Black with inclusions; Colorless in transmitted light.

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.735 - 1.745  Isotropic

Birefringence:

0.00 (Isotropic)

Dispersion:

Relatively Strong

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

A product of the high-temperature metamorphism of magnesian limestones and dolostone.

Common Associations:

Forsterite, Magnesite (Monte Somma, Italy); Brucite, Ellestadite, Hydromagnesite (Crestmore quarry, California, USA); Anhydrite, Fluorellestadite, Hematite, Lime, Magnesioferrite, Srebrodolskite, (Kopeysk, Russia).

Common Impurities:

Fe

Type Locality:

Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy

Year Discovered:

1840

View mineral photos:

Periclase Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Periclase is a very rare magnesium oxide mineral that is rarely available as a faceted gem.
It is usually found as a component of metamorphosed dolomitic limestones and readily alters to Brucite and other magnesium minerals under certain conditions. Periclase has been synthesized in large masses in the laboratory, but faceted natural Periclase would is very rare due to extreme scarcity of facetable rough.

There are a number of locations for finding Periclase but facet grade crystals may only be available from the Ronneburg U deposit, Gera, Thuringia, or the Lichtenberg Absetzer Mine (dump), Ronneburg U deposit, Gera, Thuringia, Germany.
 

  
Periclase gems for sale:

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