Chrysoberyls have been found in New South Wales; spinel rubies in New South Wales and Victoria; and white topaz in all the states.
On account of their resemblance to the twins of the mineral spinel (which crystallizes in octahedra) these are ?i D known as " spinel twins."
Among the commonest associates of the diamond are quartz, topaz, tourmaline, rutile, zircon, magnetite, garnet, spinel and other minerals which are common accessory constituents of granite, gneiss and the crystalline schists.
Associated with franklinite at Franklin Furnace, and found also at some other localities, is another member of the spinel group, namely, gahnite or zinc-spinel, which is a zinc aluminate, ZnAl 2 O 4, with a little of the zinc replaced by iron and manganese.
Twinning according to the first law is effected by rotation about an axis normal to the sphenoidal face (III), the resulting form resembling the twins of blende and spinel.
