Chrysoberyls have been found in New South Wales; spinel rubies in New South Wales and Victoria; and white topaz in all the states.
Titanium is often present, and occasionally the mineral contains magnesium, nickel, &c. It is always strongly magnetic. Magnetite crystallizes in the cubic system, usually in octahedra, less commonly in rhombic dodecahedra, and not infrequently in twins of the " spinel type " (fig.
Spinel, gahnite, &c.
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.
FRANKLINITE, a member of the spinel group of minerals, consisting of oxides of iron, manganese and zinc in varying proportions, (Fe, Zn, Mn)"(Fe, Mn) 2"'0 4.
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.