Larvikite

Larvikite is a very alkaline intrusive volcanic rock, specifically a variety of monzonite, notable for the presence of up to thumbnail-sized crystals of feldspar. These feldspars are known as ternary because they contain significant components of all three endmember feldspars. The feldspar has partly unmixed on the micro-scale to form a perthite, and the presence of the alternating alkali feldspar and plagioclase layers give its characteristic silver-blue schiller effect (called labradorescence).

It is used for countertops, carvings and jewelry as it occurs in a massive formation where large pieces can be recovered.