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Formula: Mn2+SiO3
Inosilicate (chain silicate), manganese-bearing mineral, high temperature, low pressure
paramorphs of
pyroxmangite (Mindat).
Crystal System: Triclinic
Specific gravity: 3.57 to 3.76 measured, 3.726 calculated
Hardness: 5½ to 6½
Streak: White
Colour: Red, pink, brownish-red, gray
Solubility: Slightly soluble in hydrochloric acid
Common impurities: Al,Ca,Fe,Zn
Environments:
Sedimentary environments
Metamorphic environments
Hydrothermal environments
Rhodonite is found in manganese bearing deposits formed by hydrothermal,
contact and
regional metamorphic and
sedimentary processes.
Localities
At the Rosebery Mine, Rosebery, Rosebery district, West Coast municipality, Tasmania, Australia, rhodonite occurs
with spessartine, pyrophanite,
rhodochrosite, quartz,
biotite, feldspar,
galena and sphalerite
(AJM 21.1.69).
The Ma On Shan Mine, Ma On Shan, Sha Tin District, New Territories, Hong Kong, China, is an abandoned
iron mine, with
both underground and open cast workings. The iron ores contain
magnetite as the ore mineral and occur predominantly as masses of all sizes
enclosed in a large skarn body formed by contact metasomatism of
dolomitic limestone at the
margins of a granite intrusion. In parts of the underground workings
magnetite is also found in
marble in contact with the
granite. The skarn rocks
consist mainly of tremolite,
actinolite, diopside and
garnet.
Rhodonite occurs occasionally in the skarn rocks as irregular masses
associated with tremolite-actinolite
(Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
The type locality is the Kaiser Franz Mine, Schävenholz, Elbingerode, Oberharz am Brocken, Harz, Saxony-Anhalt, Germany.
Alteration
braunite to hausmannite, rhodonite
and O2
2Mn2+Mn3+6O8(SiO4) ⇌ 4Mn2+Mn3+2O4 + 2Mn2+SiO3 + O2
A higher temperature favours the forward reaction
(AM80.565).
braunite and CO2 to rhodochrosite,
rhodonite and O2
2Mn2+Mn3+6O8(SiO4) + 12CO2 ⇌ 12MnCO3 +
2Mn2+SiO3 + 3O2
A higher temperature favours the forward reaction
(AM80.565).
braunite and quartz to rhodonite and O2
2Mn2+Mn3+6O8(SiO4) + 12SiO2 ⇌ 14Mn2+SiO3 +
3O2
A higher temperature favours the forward reaction
(AM80.565).
hausmannite and quartz to rhodonite
and O2
2Mn3O4 + 6SiO2 ⇌ 6Mn2+SiO3 + O2
A higher temperature favours the forward reaction
(AM80.571).
hausmannite and rhodonite to tephroite
and O2
2Mn3O4 + 6Mn2+SiO3 ⇌ 6Mn2+2SiO4 + O2
A higher temperature favours the forward reaction
(AM80.565).
johannsenite and H2O to rhodonite and
xonotlite
6CaMnSi2O6 + H2O → 6Mn2+SiO3 +
Ca6Si6O17(OH)2
At Pueblo, Mexico, johannsenite occurs in calcite
veins in rhyolite and is altered to rhodonite and
xonotlite
according to the above equation
(DHZ 2A p421).
manganosite and quartz to rhodonite
MnO + SiO2 ⇌ Mn2+SiO3
(AM80.561)
manganosite and rhodonite to tephroite
MnO + Mn2+SiO3 ⇌ Mn2+2SiO4
(AM80.560-575)
rhodochrosite and quartz to
rhodonite and CO2
MnCO3 + SiO2 ⇌ Mn2+SiO3 + CO2
This is a metamorphic reaction occurring in manganese deposits and manganese-rich iron formations. A higher temperature favours
the forward reaction
(MOM p487, AM80.568).
rhodonite and braunite to tephroite
and O2
10Mn2+SiO3 + 2Mn2+Mn3+6O8(SiO4) ⇌
12Mn2+2(SiO4) + 3O2
(AM80.571)
rhodonite and rhodochrosite to
tephroite and CO2
Mn2+SiO3 + Mn(CO3) → Mn2+2(SiO4) +
CO2
A higher temperature favours the forward reaction
(DHZ 1A p344, 348, AM80.571).
tephroite and quartz to rhodonite
Mn2+2(SiO4) + SiO2 → 2Mn2+SiO3
(AM80.571)
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