This is a beautiful polished slice of ruby zoisite, from Tanzania, Africa.

Technically a metamorphic rock, ruby zoisite or anyolite  is a naturally occurring combination of both ruby and zoisite crystals in a single stone. Zoisite provides an earthy green color, while ruby inclusions give the stone pink or red highlights. It often also contains black streaks of the mineral Pargasite.

Ruby zoisite is found in only a single area bordering Kenya and Tanzania near Mount Kilimanjaro. It was discovered in 1954 by an English prospector who initially thought he had found a massive deposit of rubies. Upon closer inspections the rubies within the zoisite proved to be opaque and not suitable as gemstones.