Pyroxenes in less altered dolerites are generally subhedral to eumorphic and may occur as discrete crystals as well as aggregates. The phenocrysts often enclose subophitically, laths of calcic-plagioclase of andesine composition. Cracks and fractures of pyroxene may be filled by secondary calcite. Pyroxene is generally augite and may marginally alter to hornblende. However, pyroxene and olivine are rare minerals and may occur only as relics in dolerites.