It doesn't usually make sense to talk about a material as being 'renewable'. For all practical purposes, matter is never created or destroyed. You can refine malachite into copper, and over time (lots of time) the refined copper will corrode back into malachite. read more
Malachite is a biome-specific Gemstone introduced with Biomes O'Plenty. It appears as an ore, an item, and a decorative block. Malachite Ore can be discovered in certain swampy biomes. A current list of these biomes can be found under Malachite Biomes. read more