realgar |
| noun - (mineralogy) a mineral, arsenic sulfide (AsS?), often associated with orpiment and stibnite in lead, silver and gold ores
| | rhodochrosite |
| noun - (mineralogy) a crystalline mineral composed mainly of manganese carbonate MnCO?3
| rhodonite |
| noun - (mineralogy) a manganese inosilicate mineral of composition MnSiO?3 with some substitution by iron and magnesium
| rutile |
| noun - (mineralogy) the most frequent of the three polymorphs of titanium dioxide, crystalizing in the tetragonal system
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