This is the polished amphibolite pebble. Dimensions: 2.6 x 2.0 x 0.7″ (6.5 x 5.2 x 1.9cm). Weight – 4oz (114 grams). Origin: Russia, Siberia.
Some information about amphibolite:
Amphibolite is a metamorphic rock that contains amphibole, especially the species hornblende and actinolite, as well as plagioclase.
Amphibolite is a grouping of rocks composed mainly of amphibole and plagioclase feldspar, with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance.