Ceruleite
Current inventory:  0 gems
 

  
Ceruleite is named from the Latin word caeruleus, for "sky-blue" in allusion to its common color.

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

Chemistry

Chemical Formula:

Cu₂Al₇(AsO₄)₄(OH)₁₃•12(H₂O)

Hydrated Copper Aluminum Arsenate Hydroxide

Molecular Weight:

1,308.92 gm

Composition:

Aluminum

14.43 %

Al

27.26 %

Al₂O₃

Copper

9.71 %

Cu

12.15 %

CuO

Arsenic

22.90 %

As

35.12 %

As₂O₅

Hydrogen

2.85 %

H

25.46 %

H₂O

Oxygen

50.12 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/D.20-20

Nickel-Strunz 10th Ed. ID:

8.DE.25

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H₂O
E : With only medium-sized cations, (OH, etc.):RO₄ = 3:1

Related to:

None

Varieties:

None

Synonyms:

Céruléite, Coerulite

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

As rodlike crystals, to 5 µm, in powdery to compact, clay-like, massive concretions and in spherical aggregates, to 10 cm.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

n/a

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

2.70 - 2.80 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Readily soluble in acids.

Optical Properties

Color:

Sky-Blue to pale Blue, Turquoise-Blue

Transparency:

Translucent to Opaque

Luster:

Vitreous

Refractive Index:

n = 1.60  Biaxial ( ? )

Birefringence:

0.00

Dispersion:

Weak; r < v

Pleochroism:

None

Occurances

Geological Setting:

In the oxidized zone of arsenic-rich polymetallic mineral deposits; a post-mine product.

Common Associations:

Alumopharmacosiderite, Olivenite, Schlossmacherite, Mansfieldite, Quartz (Emma Louisa mine, Chile); Mansfieldite, Quartz, Barite, Goethite (Bolivia); Liroconite, Clinoclase, Olivenite (Wheal Gorland, England); Posnjakite, Scorodite, Metazeunerite, Cassiterite, Tourmaline, Quartz (Wheal Maid, England); Malachite, Azurite, Olivenite, Mansfieldite, Pharmacosiderite (Cap Garonne mine, France).

Common Impurities:

None

Type Locality:

Emma Luisa Mine, Guanaco (Huanaco), Santa Catalina, Antofagasta Province, Antofagasta Region, Chile

Year Discovered:

1900

View mineral photos:

Ceruleite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Ceruleite is a very rare arsenate mineral that is rarely found in any size to be fashioned into a gem. It is typically found as extremely minute rodlike crystals or clay-like crusts or concretions covering matrix. The only material that could be used for making a cabochon were small, opaque, solid nodules from a one time find at the Emma Luisa mine, Guanaco, Antofagasta, Chile. Ceruleite is found associated with Mansfieldite and Schlossmacherite at this location. These two minerals are also rare arsenates.

Ceruleite is found at just a few key locations worldwide including the type locality at Emma Louisa gold mine, Guanaco district, about 100 km east-northeast of Taltal, Antofagasta, Chile. At an unknown locality in southern Bolivia. In England, at Wheal Gorland and Wheal Maid, Gwennap, and in the Penberthy Croft mine, St. Hilary, Cornwall. From the Cap Garonne mine, near Le Pradet, Var, France. At the Anticline prospect, 11 km west-southwest of Ashburton Downs homestead, Capricorn Range, Western Australia. From Tsumeb, Namibia.
 

  
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