Realgar
>
Realgar, also known as ″arsenic blende″, ″ruby sulphur″ or ″ruby of arsenic″, is an arsenic sulfide mineral with the chemical formula α-As₄S₄. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery... Wikipedia
Color: Red to yellow-orange; in polished section, pale gray, with abundant yellow to red internal reflections
Cleavage: Good on; less so on,,, and
Crystal class: Prismatic (2/m); (same H-M symbol)
Crystal habit: Prismatic striated crystals; more commonly massive, coarse to fine granular, or as incrustations
Crystal system: Monoclinic
IMA symbol: Rlg