Alacránite
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Alacránite is an arsenic sulfide mineral first discovered in the Uzon caldera, Kamchatka, Russia. It was named for its occurrence in the Alacrán silver/arsenic/antimony mine. Pampa Larga, Chile. It is generally more rare than realgar and orpiment.... Wikipedia
Color: Orange to pale gray, rose-yellow internal reflections
Crystal class: Prismatic (2/m); (same H-M symbol)
Crystal habit: Equant grains
Crystal system: Monoclinic
Formula (repeating unit): As8S9