A microcline feldspar. Microcline is a K-feldspar (part of a solid solution series between sodium and potassium). These samples have a strong perthitic structure, where albite has exsolved from the lattice during cooling.
Average weight, 5g. All pieces are of the same size and similar quality. All prices are per item. Photographs are representative of the items on offer, but the item you buy may not be the one in the photograph