TRIGONAL
subdivision of hexagonal system
Antimony
Arsenic
Bismuth
Calcite
Chalcedony
Dolomite
Gaspeite
Jarosite
Magnesite
Natrojarosite
Otavite
Quartz
Rhodochrosite
Siderite
Smithsonite
Sphaerocobaltite
Stibarsen
Tellurium
Tincalconite
Tourmaline
Many more to come soon!