What occurred to form this malachite specimen?

The banded specimens are formed by massive, botryoidal, reniform, and especially stalactitic Malachite that are dense intergrowths of tiny, fibrous needles. ... Crystal Forms and Aggregates, Most common habit is as large crusts of microscopic crystals. Also occurs as bundles of thin long splinters. read more

I think it's just the way that the crystals grew to form the banding. A random theory: Malachite can grow like stalactites, so if the stalactites were cut off, they might have concentric circles. read more

Malachite is a mineral that forms at shallow depths within the Earth, in the oxidizing zone above copper deposits. It precipitates from descending solutions in fractures, caverns, cavities, and the intergranular spaces of porous rock. read more

You are bidding on (1) free form hand polished Malachite gemstone specimen from the Democratic Republic of the Congo. The Congo, is know to produce the nicest Malachite in the world. Pictured are random specimens that average (1/8) pound each. Each specimen averages about 1". Some are a littler smaller and most are larger. read more