Romanèchite

Romanèchite is named after its discovery locality, at Romanèche (now Romanèche-Thorins), 20 km west of Villefranche, Saône-et-Loire, France.

Romanèchite forms iron-black, dark steel-gray masses, crystals are very rare.

Romanèchite is used for ornamental purposes.
General Information
Chemical Formula
(Ba,H
 
2
O)
 
2
(Mn
4+
 
,Mn
3+
 
)
 
5
O
 
10
Anthony et al, Handbook of mineralogy (2001)
Photos of natural/un-cut material from mindat.org
Physical Properties of Romanèchite
Mohs Hardness5 to 6
Anthony et al, Handbook of mineralogy (2001)
Specific Gravity4.70 to 4.74
Anthony et al, Handbook of mineralogy (2001)
Optical Properties of Romanèchite
Optical CharacterBiaxial
Anthony et al, Handbook of mineralogy (2001)
BirefringenceStrong; gray to white
Anthony et al, Handbook of mineralogy (2001)
Colour
Colour (General)Iron-black, dark steel-gray; gray-white in reflected light.
Anthony et al, Handbook of mineralogy (2001)
TransparencyOpaque
Anthony et al, Handbook of mineralogy (2001)
LustreDull (Earthy),Submetallic
Anthony et al, Handbook of mineralogy (2001) Submetallic; dull when massive
Crystallography of Romanèchite
Crystal SystemMonoclinic
Anthony et al, Handbook of mineralogy (2001)
HabitEuhedral crystals very rare, flat, ridged, to 200 µm; acicular to fibrous, divergent; commonly reniform, botryoidal, stalactitic, colloform banded; very fine-grained massive.
Anthony et al, Handbook of mineralogy (2001)
Geological Environment
Where found:A product of weathering of manganese bearing oxides, carbonates, silicates; in sedimentary deposits; as replacement deposits in limestones and dolostones; a principal component of "psilomelane" and "desert varnish" (manganese oxide-rich coatings formed on rocks in arid regions); in some plume agates.
Anthony et al, Handbook of mineralogy (2001)
Further Information
Mineral information:Romanèchite information at mindat.org
Significant Gem Localities
France
 
  • Bourgogne-Franche-Comté
    • Saône-et-Loire
      • La Chapelle-de-Guinchay
        • Romanèche-Thorens
Mexico
 
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.