BICOLOUR TOURMALINE CRYSTALS
Beautiful Bicolour Tourmaline Crystals. Some would call this specimen a Water Melon Tourmaline. A little pale with Pink at the bottom of large crystal and Green at the tip of small crystal. Still a good Specimen at a bargain price.
2.3cm x 2.4cm x 2.1cm, 13g.
The Tourmaline Group has a general formula of AX3Y6(BO3)3 Si6O18(O, OH, F)4. The A can be either calcium or sodium. The X can be either aluminum, iron, lithium or magnesium. The Y is usually aluminum, but can also be chromium or iron. Some potassium can be in the A position, some manganese can be in the X position and some vanadium can be found in the Y position, but these elements are usually not represented in the formulas of the tourmaline members.