Coronadite
Current inventory:  0 gems
 

  
Coronadite was named in 1904 by Waldemar Lindgren and William F. Hillebrand to honor Francisco Vasquez de Coronado (1510-1554), a Spanish conquistador and explorer of the American southwest.

Discovered in 1904; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Pb(Mn⁴⁺,Mn²⁺)₈O₁₆

Lead Manganese Oxide

Molecular Weight:

933.55 gm

Composition:

Barium

1.47 %

Ba

1.64 %

BaO

Manganese

45.31 %

Mn

3.80 %

MnO / 67.05 % MnO₂

Aluminum

0.29 %

Al

0.55 %

Al₂O₃

Vanadium

1.09 %

V

1.95 %

V₂O₅

Lead

24.41 %

Pb

26.30 %

PbO

Oxygen

27.42 %

O

100.00 %

101.29 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.08-70

Nickel-Strunz 10th Ed. ID:

4.DK.05a

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
K : With large (+- medium-sized) cations; tunnel structures

Related to:

Coronadite Group (synonym: Cryptomelane Group). Hollandite Supergroup. Isostructural with Hollandite and Cryptomelane.

Members of Group:

Coronadite Group: Coronadite, Cryptomelane, Ferrihollandite, Hollandite, Manjiroite, Strontiomelane 

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As fibrous botryoidal aggregates, banded with other manganese oxides; as microscopic curved lamellae; laminated, granular, massive. 

Twinning:

None

Physical Properties

Cleavage:

n/a

Fracture:

n/a

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.0

Density:

5.246 - 5.505 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Dark gray to black; white in reflected light

Transparency:

Opaque

Luster:

Dull to submetallic

Refractive Index:

Biaxial 

Birefringence:

0.000 (opaque)

Dispersion:

Strong; r > v

Pleochroism:

Strong; dark brown to gray

Anisotropism:

Strong; nearly Galena-white

Occurances

Geological Setting:

A primary mineral in hydrothermal veins or from hot springs; of secondary origin in oxidized zones above manganese-bearing rocks; also in bedded sedimentary deposits.

Common Associations:

Hollandite, Pyrolusite, other manganese oxides

Common Impurities:

Fe, Al, H₂O

Type Locality:

Horse-Shoe shaft (Horseshoe Mine), Coronado Mine (Coronado Mining Co. property; Arizona Copper Co. group [in part]), Coronado vein, Copper Plate Gulch, Copper Mountain District (Clifton-Morenci District), Shannon Mts, Greenlee County, Arizona, USA

Year Discovered:

1904

View mineral photos:

Coronadite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Coronadite is a black metallic lead manganese oxide mineral that is a member of the Coronadite Group of minerals that also includes Hollandite, among others. Coronadite gems are somewhat rare only because there is little demand for them other than as an unusual collector gem. Faceted gems are rather attractive however, with dark gray to black color and submetallic luster that looks white in reflected light.

Coronadite was first described and named in 1904 by Waldemar Lindgren and William F. Hillebrand from material found on the dump of a small mine shaft on the west end of the Coronado vein, three-fourths of a mile west of Horseshoe shaft of the Coronado Mine, Clifton-Morenci district, Greenlee County, Arizona, USA. Lindgren and Hillebrand proposed the name "Coronadite" to honor Francisco Vasquez de Coronado (1510-1554), a Spanish conquistador and explorer of the American southwest who had visited the region in 1540. Hillebrand said: "We propose the name Coronadite, after the famous explorer of that portion of the American continent from which the Territories of New Mexico and Arizona have been formed." They described Coronadite as "a black metallic mineral, not unlike Psilomelane in general appearance, and intemately intermixed with Quartz, is found in fairly large amount in the Coronado vein."

Coronadite distribution: Widespread; a few localities for pure or well-characterized material include: in the USA, in Arizona, from the Coronado vein, Clifton-Morenci district, Greenlee County; the Magma mine, Superior, Pinal County; from the Artillery Mountains, Mohave County, and elsewhere. In New Mexico, from the Luis Lopez district, Socorro County. From the Philipsburg district, Granite County, Montana. In Mexico, from the Talamantes district, Chihuahua, and in the Ojuela mine, Mapimí, Durango. At many places in the Ouarzazate and Oujda districts, and elsewhere in Morocco. From the Almalyskoye Pb–Zn deposit, Kurgashikan, Uzbekistan. In the Dry Gill mine, Caldbeck Fells, Cumbria, England. In France, from the Richesse mine, near Bourgeten-Huile, Savoy. At Dongari Buzurg, Bhandara, Madhya Pradesh, and Kodur, Andhra Pradesh, India. From Broken Hill, New South Wales, and in the Puttapa zinc mine, near Beltana, South Australia. At Tsumeb, Namibia.
 

  
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