Encyclopedy Index |
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Rapakivi granite is a hornblende-biotite granite containing large rounded crystals of orthoclase mantled with oligoclase. The name has come to be used most frequently as a textural term where it implies plagioclase rims around orthoclase in plutonic rocks. Rapakivi is Finnish for rotten or crumbly rock and describes the tendency of the rapakivi granite to easily weather. ![]() Rapakivi is the material used in Ålands Middle Age stone churches. |
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