About the History and Properties of Garnets and Their Varieties

Garnet is a noun that is applied to a variety of gem minerals red or brownish-red. Almandite, a stone of rich cherry, claret, or blood-red colour is the precious garnet. A variety of garnet recently established that is in high favour is rhodolite. The chemical bases of both of these leading varieties are the same, a silicate of iron and aluminium. Precious garnet has a hardness of about 7.5, with a specific gravity seldom less than 4. and occasionally as high as 4.3. Closely following almandite, or as jewellers call it, "almandine," in the favour of gem fanciers, is Bohemian garnet or pyrope, meaning "fire-like"; this has a range of colour from a deep blood red to almost black. Pyrope is slightly harder than almandite, and its specific gravity lies between 3.7 and 3.8. The fracture is brittle; refraction, single; lustre, vitreous; it is transparent to opaque. Most varieties of garnet fuse to brown or black glass.

In Dana's Mineralogy, Garnet is Carbunculus dodecahedrus: order Hyalina. In crystallography the primary form of garnet is the rhombic dodecahedron. The cleavage is indistinct parallel with the faces of the dodecahedron. Besides the primary twelve-sided form, with rhombic faces, the secondary forms of garnet crystals include trapezohedrons--twenty-four-sided forms--with faces shaped like trapeziums; then there are combinations of these forms, one of which has thirty-six faces. The tendency of garnet is to crystallise and it is usually found in crystals; these range from tiny ones the size of a grain of sand up to those of several pounds in weight.

The name garnet, according to one version, is derived from the Latin granatus, meaning like a grain, because of the resemblance of its crystals in size and colour to the seeds of the pomegranate.

A carbuncle, in the popular conception, is a specific precious stone, but it does not exist in scientific mineralogy, and in the verbiage of dealers now, its meaning is merely any worthy red translucent stone cut en cabochon. Some writers, who seem otherwise generally well in formed, have fallen into this common error of recognising the word carbuncle as the name of a specific gem. Probably almost any fiery-red translucent ornamental stone in the days of ancient Rome was called carbunculus, derived from carbo, coal, and the name was bestowed because of the internal fire-like colour and reflection which is a common characteristic of the various stones now generally termed garnets. The garnet is among the stones earliest mentioned in the surviving literature of all ancient languages.

Almandite derives its names from Alabanda, a city in the ancient district of Caria, Asia Minor; whence garnets were introduced to ancient Rome. The most highly valued specimens of almandite, for a long period, came from localities not known to the western world, but they were supposed to be mined near the city of "Sirian" in old Pegu province, Lower Burma, and were called "Sirian garnets." So careful an investigator and high an authority as Dr. Max Bauer, in his monumental work on precious stones, states that Syriam, the ancient capital of Pegu, is now but a small village in the British province of Lower Burma near the great trade centre of Rangoon. A resume of the facts evolved by Dr. Bauer shows that no precious almandite occurs in any part of Burma, while in Upper Burma the only red stones found are ruby, spinel, and red tourmaline. Long ago, therefore, Syriam was merely a distributive point for garnets brought to its market from a distance, possibly from the Shan states to the eastward. The "Sirian" garnet is now merely a type; it tends toward a violet colour.

In northern India almandite is mined on an extensive scale in several localities. The stone is found in the Alps, Australia, and Brazil; a variety too opaque to be very valuable, occurs plentifully on the Stickeen River in Alaska. Metamorphic rocks, such as gneisses or mica schists, granite, and gem gravels are the usual environments of almandite.

Rhodolite is an intermediate between almandite and pyrope, more closely related to the latter, but differing in colour from both. It is found as water-worn pebbles in the gravels of Cowee Creek and Mason's Branch, Macon County, North Carolina; sometimes it occurs along with ruby in a decomposed, basic igneous rock, known as "saprolite"; a curious occurrence is in the form of small crystals enclosed in crystals of ruby. The colour resembles that of the rhododendron, from which this but recently recognised precious stone was christened rhodolite. Although mineralogically different from almandite, and more like pyrope, rhodolite is known in the trade as "almandine," and, in the United States at least, is bought and sold under that title; the difference in composition and colour is too slight for merchant jewellers to recognise, and the name "rhodolite" is scarcely known to the trade or the general public. In fact, in the jewelry trade, any garnet with a tendency toward a violet colour is classed as an "almandine." Under the name "almandine," there has been an increased demand for this variety of garnet for medium-priced jewelry for about five years previous to this writing.

Scarcely second to almandite, is the dark blood-red pyrope, Found in company with the diamond in South Africa, and, in the trade, called "Cape Ruby." This fine South African gem stone, companion of the diamond and native to the world's greatest diamond fields, is a magnesium-aluminium garnet, containing manganese oxide and ferrous oxide; its specific gravity is 3.86, approximating that of the Bohemian pyrope, which it resembles in both chemical composition and colour, thus clearly classing it as pyrope, and not almandite, as was done for some time after its discovery. In the trade at present this variety of garnet commands a higher price than any other.

Varieties of the lime-aluminium garnet occasionally appear in gem-stone commerce. Lime-aluminium garnet has a hardness of 2.7, and a specific gravity of 3.55 to 3.66. Its colours are white, pale green, amber, honey, wine, brownish-yellow, cinnamon, brown, and pale rose-red. The varieties include essonite and cinnamon stone, the latter often improperly called, by merchants, "hyacinth." The gem cinnamon stones come chiefly from Ceylon; they are of a cinnamon brown, or range from that to a deep gold colour tinged with brown. Grossularite includes the pale green, yellow to nearly white, pale pink, reddish or orange, and brown kinds. Romansovite is brown. Wilnite is yellowish-green to greenish-white. Topazolite is topaz, to citrine, yellow. Succinite is amber coloured. There are two kinds of calcium-iron or green garnets: The demantoid, from the Ural Mountains, Siberia, has a hardness of 6. to 6.5; specific gravity, 3.83 to 3.85. Demantoids have a rich green colour and when clear and flawless are beautiful lustrous gems; the choicest are called "olivines." The other green variety, Uvarovite, is found chiefly in Russia. Montana ruby is a trade term for the fine garnets found in Montana and Arizona. The finest American garnets are found in the territory of the Navajo nation in north-western New Mexico and north-eastern Arizona, where they are collected from ant-hills and scorpions' nests by Navajo Indians and sometimes by United States soldiers from adjacent forts. According to the most eminent authority on American gem stones, Dr. George Frederick Kunz, these red stones, known locally as Arizona and New Mexico rubies, are unsurpassed, equalling in value those from the Cape of Good Hope. Fine gems weighing two and three carats, after cutting, are not rare. By artificial light the American stones are superior to "Cape rubies." These American garnets have evidently recently weathered out of a peridotic rock.