Aluminium oxide

And six divided by charge on aluminum three gives you two aluminums.

So Al2O3, aluminum oxide.

Manganese, Roman numeral four would be Mn positive four and sulfate SO4 minus two.

You're going to need two sulfates to bond with the manganese.

Alpha adamantine, or the peculiar lustre of the diamond, so called from the lustre of adamantine spar, which is a form of corundum, as is emery, with a diamond-like lustre, the hard powder of which is used in polishing diamonds.

It is almost pure anhydrous alumina, Al2O3, and is roughly four times as heavy as water.

The lustre of this is the true adamantine or diamond brilliancy, and the other and impure divisions of this particular lustre are splendent, when objects are reflected perfectly, but of a lower scale of perfection than the true adamantine standard, which is absolutely flawless, when still lower, and the reflection, though maybe fairly good, is somewhat fuzzy, or is confused or out of focus, it is then merely shining, When still less distinct, and no trace of actual reflection is possible, by which is meant that no object can be reproduced in any way to define it, as it could be defined in the reflection from still water or the surface of a mirror, even though imperfectly, the stone is then said to glint or glisten.

When too low in the scale even to glisten, merely showing a feeble lustre now and again as the light is reflected from its surface in points which vary with the angle of light, the stone is then said to be glimmering.

A further form of lime-iron garnet is the pyrenite, first found in the Pyrenees Mountains, hence its name.

the c lime chrome garnets six c a o comma three s i o two plus two c r two o three comma three s i o two the chief of which is owarra white this is of a magnificent emerald green colour translucent at edges and of a vitreous lustre when heated on the borax bead it gives an equally beautiful green which is however rather more inclined to chrome than emerald This is an extremely rare stone in fine colour, though cloudy and imperfect specimens are often met with, but seldom are large stones found without flaws and of the pure colour which rivals that of the emerald in its beauty.

The fourth variety, D, is the lime alumina garnet, its formula being 6 CaO, 3 SiO2, plus 2 Al2O3, 3 SiO2.

Like the others, it has a number of sub-varieties, the chief being the cinnamon stone, which is one of great beauty and value when perfect.