Description of colouring and granulometry: granite characterized by a very peculiar petrographic structure called rapakiwi with a very coarse to coarse grain;
it has a streaked and variable appearance with numerous feldspar orthoclase crystals of an oval or round shape and a brown or pinkish-brown colour, surrounded
by thin borders of feldspare oligoclase. The interstices between the spherical aggregates contain fine-grained masses of black biotite, grey quartz and dark green
hornblende. Biotite is also present in the form of small scales in the feldspar crystals. For this reasonthe appearance of this rock has strong contrasts. The high
cost of this stone is due to the great difficulty in finding valuable stone that, besides being available in large quantities, does not undergo significant variations in
quality over time. It is quarried in Finland, in the large granite mass forming part of the Finnish-Scandinavian crystalline shield, south of Lappeenranta, near the
border with Russia, in the Lahnajarvi and Hujakkala districts of the Ylamaa region.
Other commercial names: Baltic Brown, Rapakiwi Brown, Baltico Marrone.
Prevailing applications: interior and exterior – wall cladding, flooring, slabworks and monumental art.
Mineralogical composition (weight %): potash feldspar 55, quartz 25, plagioclase 11, biotite 4 and horneblende 5.
Physical and mechanical properties: volumetric weight: 2679-2690 kg/m3; porosity: 0.44%; water absorption: 0.14-0.16 (weight %); compressive strength:
148.1-170.8 MPa; mechanical bending strength: 4.9-11.9 MPa; thermal expansion: 0.5-0.9 mm/mx100°C; abbrasion resistance:54.68; breaking modulus:
10.73-13.8 MPa; wear for abrasion according to Boehme: 5-8 cm3/50cm2; Mohs hardness: 6.
Collection: materials, manufacturing and uses