Romanèchite is a barium manganese oxide mineral. It is the primary constituent of Psilomelane, which is a mixture of minerals. Romanèchite is commonly found associated with Pyrolusite and other manganese oxide minerals as well as Goethite, Calcite, and Quartz. Romanèchite is a valuable ore of manganese, which is an essential ingredient in steel and other alloys. It is opaque, black to dark steel-gray with sub-metallic luster and a Moh’s hardness of 5 – 6. Romanèchite specimens of black, lustrous, botryoidal masses can be quite attractive. Faceted Romanèchite gems are rare and unusual.

Romanèchite distribution: although common in occurrence, characterization by X-ray, chemical analysis, or both, is necessary. Authenticated from: Romanèche, Saône-et-Loire, France. In Germany, well-crystallized from Schneeberg, Saxony, and at the Clara Mine, near Oberwolfach, Black Forest. From the Restormel mine, Lostwithiel, Cornwall, England. In the USA, at Austinville, Wyeth County, Virginia; from Sodaville, Mineral County, Nevada; at the Hoggett mines, Hidalgo County, New Mexico; at the Tolbard mine, Paymaster district, Imperial County, California. In the Talmantes mine, near Parral, Chihuahua, Mexico. From Pilbara, Western Australia.

Category: Oxide minerals
Chemical Formula: (Ba, H2O)2Mn5O10
Hydrated Barium Manganese Oxide
Molecular Weight: 544.25 gm
Composition: Barium 17.66 % Ba 19.72 % BaO
Manganese 48.45 % Mn 69.62 % Mn2O3
Silicon 0.52 % Si 1.10 % SiO2
Hydrogen 0.44 % H 3.97 % H2O
Oxygen 34.92 % O
  100.00 % 94.41 % = TOTAL OXIDE


Crystallography: Monoclinic – Prismatic
Crystal Habit: Euhedral crystals very rare, flat, ridged, to 200 μm; acicular to fibrous, divergent; commonly reniform, botryoidal, stalactitic, colloform banded; very fine-grained massive. 
Twinning: None


Cleavage: None
Fracture: Irregular/uneven
Tenacity: Brittle
Moh’s Hardness: 5.0 – 6.0; Vickers: VHN100=514-715 kg/mm2
Density: 4.70 – 4.74 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive


Color: Iron-black, dark steel-gray; gray-white in reflected light
Transparency: Opaque
Luster: Sub-metallic, dull when massive
Refractive Index: R1–R2: (400) 26.7–38.7, (420) 26.3–37.7, (440) 25.6–35.9, (460) 25.2–34.8, (480) 24.8–34.0, (500) 24.3–33.0, (520) 23.8–32.1, (540) 23.4–31.1, (560) 22.9–30.1, (580) 22.4–29.3, (600) 22.0–28.6, (620) 21.6–28.0, (640) 21.3–27.5, (660) 21.2–27.2, (680) 20.9–26.8, (700) 20.7–26.5


Birefringence: None
Dispersion: None
Pleochroism: None
Anisotropism: Strong. Bireflectance: Strong; gray to white.