mineral
Tumbled orange-brown feldspar, likely sunstone or aventurine feldspar
Potassium feldspar, commonly orthoclase or oligoclase; approximate composition KAlSi₃O₈–NaAlSi₃O₈
AI-generated identification · may be incorrectHardness 6–6.5 Mohs; orange-brown, translucent to opaque, with a vitreous to resinous polish and whitish internal cleavage or inclusions. Feldspar is tectosilicate with two good cleavage directions, though these are obscured by tumbling.
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Physical properties
Hardness 6–6.5 Mohs; orange-brown, translucent to opaque, with a vitreous to resinous polish and whitish internal cleavage or inclusions. Feldspar is tectosilicate with two good cleavage directions, though these are obscured by tumbling.
Formation & geological history
Formed by crystallization from silica-rich igneous melts, commonly in granitic or pegmatitic rocks; individual grains may be Precambrian to younger. Orange color can result from iron-bearing inclusions, while true sunstone may show aventurescence from reflective platelets.
Uses & applications
Used primarily as a decorative, lapidary, and jewelry stone; feldspar is also important industrially in glass and ceramic manufacture. This small tumbled piece has modest specimen value.
Geological facts
The appearance is consistent with orange feldspar but cannot confirm visible aventurescence from the photograph alone. It may also be sold commercially as orange aventurine feldspar or Oregon sunstone rough/tumbles.
Field identification & locations
Identify by its salmon-orange color, moderate hardness, feldspar cleavage, and occasional glittering schiller; it should scratch glass but not quartz. Common sources include Oregon, India, Tanzania, Madagascar, and granitic pegmatites worldwide.
