Tourmaline - Black / Green: crystal

I bought this tourmaline crystal for the interesting base rather than its termination! The tourmaline appears to be black - although the finer crystals around the base show as green-black. The base has many needle-like crystals grouped tightly together, their varying lengths showing how they have grown amidst the groundmass, which I think is cleavelandite / albite, with a few plates of mica.
Size: 6 x 4 x 3.75 cm