This is a rare form of volcanic glass, obsidian. The appearance is very enamel like. The really unusual thing about this is that this is a low silica obsidian, which seems like a contradiction in terms. There are three specimens included. This is sometimes called basalt glass. Tachylite with this appearance is very uncommon, as far as I have knowledge, this location has produce some of the prettiest and most uncommon material in the world. The late Bill Hartley of Ashford, NSW, had some piece of this material with a rainbow like enamel surface. There are two tachylite specimen included for sale. This material is mentioned in George Smiths Mineralogy of NSW (Page 76), but as I said today this is rarely seen stuff. Ex Gary Farnham collection.
LARGEST PIECE 16 x 10 x 5.5mm.