A specimen of clinoatacamite, hosting numerous dark green crystals of the mineral set against a vug lined with contrasting quartz over bits of malachite. 

This is one of the top two clinoatacamites from the lot (along with the first specimen on the page, which I would consider the best.)  The other specimen has more clinoatacamite and is larger, but I think this one might have better aesthetics.

The majority of the examples I have seen have the crystals somewhat jumbled together, or set against dark green malachite matrixes.  As a result, the crystals can be hard to properly appreciate.  The contrasting background and distinct nature of the crystals and crystal clusters make the clinoatacamite on this piece easier to discern and appreciate.

I purchased a large lot of Lilly Mine material while in Peru, the bulk of the specimens were mainly just druses of quartz over chrysocolla or malachite, though there were a small quantity of these very rare clinoatacamite specimens as well.

This is one of the top two clinoatacamites from the lot and an unusual example of the intersection between rarity and a macroscopic mineral that can actually be called aesthetic.  

Clinoatacamite is a hydrous copper chloride