Froland Ruby
Image: <a href="//commons.wikimedia.org/w/index.php?title=User:Fennefoss_geomuseum&action=edit&redlink=1" class="new" title="User:Fennefoss geomuseum (page does not exist)">Fennefoss geomuseum</a> (CC BY-SA 4.0)
Mineral NameFroland Ruby
Chemical FormulaAl2O3
Mohs Hardness9
Crystal Systemtrigonal
Streak Colorwhite
CleavageAbsent (parting on {0001} and {1011})
Fractureconchoidal to uneven
Specific Gravity4
Colorsred
Transparencytranslucent to opaque
Type LocalityFroland, Aust-Agder, Norway
Mineral GroupOxides
Usesgemstone, abrasive, collector's item
Associated Mineralsmica, feldspar, kyanite, zoisite, amphibole
Rarityrare
Description
A large, rough, dark-colored specimen of Froland ruby is held by a man in a museum, surrounded by other mineral displays. The specimen appears blocky and somewhat irregular in shape.
Geological Context
Ruby typically forms in metamorphic rocks such as marble, gneiss, or schist, or in certain igneous rocks like basalt, under high temperature and pressure. The Froland rubies are found in amphibolites and anorthosites within a Precambrian metamorphic complex.
