Black rock I got in a
marble cutting factory. The composition of this rock is :
plagioclase (labrador), orthopyroxene, biotite and amphibole. The
orthopyroxenes contain fine lamellae (alteration products ?) which give
this rock some bronze like reflections.
Reflection picture of a
polished section of the rock between crossed polars. The lamellae which
give this rock the metal like appearance are perfectly visible in this
section. It is similar to the metal painting of cars.
The brilliants micro
crystals are still visible on this reflection image without analyzer.