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Botryoidal Black Romanechite

The Mineral romanechite

Romanechite is sometimes synonymous with Psilomelane, but in reality Romanechite is a strictly defined mineral that is recognized by the IMA, whereas Psilomelane is not specifically identified, or is a compound of several barium manganse oxides including Romanechite. Romanechite is named after the locality of Romanèche-Thorens in France, the type locality for this mineral.
Chemical Formula (Ba,H2O)2(Mn4+Mn3+)5O10
Composition Hydrous barium manganese oxide
Color Dark gray to black
Streak Black to brownish black
Hardness 5.5 - 6
Crystal System Monoclinic
Crystal Forms
and Aggregates
Never in individual crystals. Habits include botryoidal, mammilary, reniform, stalactitic, radiating, acicular, fibrous, dendritic, arborescent, encrusting, massive, and earthy.
Transparency Opaque
Specific Gravity 4.7 - 5
Luster Submetallic, silky, dull
Cleavage None
Fracture Conchoidal, uneven, earthy
Tenacity Brittle
In Group Oxides; Hydroxides
Striking Features Color, streak, and association with other manganese minerals
Environment As a secondary mineral in hydrothermal replacement deposits, in sandstones, limestones, and clays.
Rock Type Sedimentary, Metamorphic
Popularity (1-4) 3
Prevalence (1-3) 2
Demand (1-3) 2

Romanechite AUCTIONS

Romanechite is an ore of manganese. 

Romanechite occurs in many manganese deposits, though most often in uninteresting habit and not necessarily identified. The type locality for Romanechite is Romanèche, Saône-et-Loire, France. Other important localities include the Clara Mine, Oberwolfach, Black Forest, Baden-Württemberg, Germany; the Adam Heber Mine, Neustädtel, Schneeberg, Saxony, Germany; and an unspecified locality in Pinal Co, Arizona which has recently been producing nice specimens.

Barite, Pyrolusite, Quartz, Hematite

Pyrolusite - Most commonly in crystallized aggregates, which are lacking in Psilomelane.
Hematite - Has a red streak.
Goethite - Yellow streak, lower specific gravity, usually a darker color.

romanechite PHOTOS
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