fiery scarlet specimens, the deep red, and the crimson are commonly cut en cabochon, with a hollow at the back to receive a bit of foil; such stones are called carbuncles. A delicate silvery cross is seen in some carbuncles, which may be called star carbuncles; this star has but four rays instead of the six belonging to the star sapphire. The garnets of this variety generally show a very distinctive set of three black bands when viewed with the spectroscope.[1] This peculiarity was discovered by the present writer and published in the "Intellectual Observer" of 1866. This group of absorption bands may be made to serve as a criterion for discriminating between the red garnets of this variety and red spinels. When a red garnet is faceted the table should not be large nor the stone be left very thick or a blackish appearance will result. The almandine is said to have arisen from Pliny's adjective alabandicus, applied to the carbunculus cut and polished in the town of Alabanda, in Asia Minor. Syriam, once the capital of the ancient kingdom of Pegu, was, it appears, an important mart for fine almandines, hence the term Syriam or Syrian garnets was applied to the choicer specimens of almandine. Besides the old and numerous Indian localities of almandine, Brazil, South Australia and German East Africa furnish fine specimens.
Transparent red garnets of very large size have been fashioned into cups and boxes. Slabs of polished garnet, sometimes of considerable area, were employed as inlays in Celtic and Anglo-Saxon jewellery.
The red or precious garnets of the variety under discussion are never found with the exact theoretical composition of a pure "ferrous aluminium" garnet; there is always some admixture or replacement. But a characteristic specimen was found to contain, in 100 parts, about—
Silica | 39 | Manganous oxide | 1 |
Alumina | 19 | Magnesia | 2 |
Iron oxides | 37 | Lime | 1 |
- ↑ Frontispiece, Fig. 10.