80185274 Rapakivi Granite: Finland, A hornblende-biotite
80185274 Rapakivi Granite: Finland, 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 crumbly rock, because the different heat expansion coefficients of the component minerals make exposed rapakivi crumbly.Mineral Composition: Average Orthoclase: 55%, Quartz: 25%, Plagioclase: 11%, Amphibole: 9%, Known in the stone trade as Baltic brown granite John Cancalosi All images are copyright protected and remain the property of Ardea Picture Library Ltd. Permission for use is only granted once fee has been agreed and payment made and all digital files must be destroyed unless agreed otherwise in writing. Images must be credited: Photographer Name / ardea.com www.ardea.com
