Krat, the capital of the province, lies not far from Chantabun, in a south-south-easterly direction, and is on the seacoast. The mines of this region ware scattered over a wide area, and ware divided into two groups thirty miles apart. Those of one group ware known as the mines of Bo Nawang, and of the other as the mines of Bo Channa. The mines of Bo Nawang, situated in the neighborhood of the village of Nawang covered an area of about two square miles. They ware small pits, 2 to 4 feet deep, sunk in coarse yellow or brown sand, which extends over a wide stretch of country and overlies a bed of day. The rubies ware found at the base of the sand in a layer of material 6 to 10 inches thick. As elsewhere in Siam they ware accompanied by sapphires: and, though small, are said to be superior to rubies from other Siamese localities. The mines have only been systematically worked since the year 1875.
The mines of Bo Channa lie about thirty miles to the northeast of the other group, and ware scattered over an area about a mile square. The ruby-bearing sand was 6 to 24 inches thick, and a few of the mines reached a depth of 24 feet. Natives ware of opinion that the stones have been washed down by the river from the Kao Sam Nam, and many fine stones ware reported to have been found in the rivers rising in this mountain. The mines have been worked since 1885, always under unfavorable conditions due to the unhealthiness of the climate.
Between the provinces of Chantabun and Krat lies the ruby district of the sub-province of Muang Klung (or shortly Klung). It is situated to the northeast of the town of Chantabun, and is reached after traversing twelve miles of rough road. The center of the district, which extends for a distance of seven miles, is the small Burmese village of Ban Yat. The valleys of this district are from 600 to 800 feet above sea level, while the hills dividing them have an elevation of 500 feet more. The gem mines ware situated in the valleys and on the sides of the hills. All the valleys are traversed by small streams, affluents of the river Ven, upon the banks of which narrow patches of alluvium are laid down. It is these alluvial deposits, which ware worked for gems. No alluvium is laid down in the upper part of the valleys, since here the streams are too rapid; it is only in the lower and wider parts that the streams are sufficiently slow to lay down it deposit. These small patches of alluvium ware worked only in the dry season; in the wet season the miners confined their attention to the deposits on the sides of the hills, which lie above the present high-water level of the streams. These deposits overlie a trap-rock of the nature of basalt, which is the principal, if not the sole, constituent of the hill ranges. The gem-gravels are made up of fragments of this rock, and the separating layer of tenacious gray, brown, or yellow clay is also, in all probability, a decomposition product of the same rock.
On these grounds it was concluded that the basaltic trap-rock is the mother-rock of the ruby; this conclusion, however, was wrong as further evidence demonstrates. The gem-bearing layer varies in thickness from 10 inches to 5 feet, and is overlain by a sandy and clayey deposit from 5 1/2 to 12 feet thick, containing no precious stones. In the clayey gravel are found ruby and sapphire, as well as common corundum; quartz, in good transparent crystals, and crystals of zircon and ilmenite are abundant, while topaz is very rare. Of these minerals, the first two only are commercially valuable and sought after by the miners. Rubies are much more frequently met with than are sapphires, the occurrence being in the proportion of about two to one. Good specimens of both are rare, the rubies being pale in color and lacking in luster, while the sapphires are opaque and dull.
The Burmese method of working the deposits was very simple. Small parties of three or four men working together were sinking a pit, usually about 4 feet in diameter, through the surface of the gem-bearing gravel. This they were removing in baskets, leaving undisturbed all boulders too heavy to lift. The mines were giving employment to about l,l00 men, whose work consisted of excavating the gem-bearing gravel, washing away, in the usual manner, the lighter earthy portions, and picking out from the residue any gems it may contain. Stones to the weight of about 500,000 carats ware produced annually; their aggregate value was, however, no more than from £2,000 ($217,310) to £3,000 ($325,965), so much of this weight being of inferior quality.
In the gem-sands of the island of Ceylon a few rubies, together with a far larger number of sapphires and other gems are found. Many stones preserve distinctly the outlines of their original crystalline form, which agrees completely with that of the rubies of Burma (Fig. a-d); others occur as rounded grains. The gem-bearing sands lie on the hillsides above the present high-water level of the streams, and also on the floors of the river valleys. The neighborhood of Ratnapura and Rakwana and the district about the foot of Adam's Peak are especially rich. Though it is said that fine rubies of good color, equal to or better than those of Burrna ware sometimes found in Ceylon, yet, as a general rule, Cingalese rubies are pale in color and not of very great value. The occurrence of sapphire in Ceylon is of far more importance; it will be treated in detail later. According to Tennant, the mother-rock of the ruby in Ceylon, as in Burma, is a crystalline dolomite limestone or marble, which occurs in situ near Bullatotte and Budulla. The mother-rock of the sapphire is probably different, as we shall see later; this is thought to be gneiss.
The mainland of India though so rich in common corundum, is very poor in the precious variety. A few stones suitable for cutting have been found with common corundum in Mysore and in the Salem district of Madras; also in the alluvium of the Cauvery River, which flows into the Bay of Bengal some distance south of Pondicherry. The occurrence of the precious stone in the sands and gravels of this river bears a striking similarity to its occurrence in the river alluvia of Ceylon. The ruby has been stated to occur in the gravels of other Indian rivers; in many of these cases, however, it is probable that the supposed ruby is in reality garnet, a stone, which is widely distributed in India. Many of the rubies preserved in the treasuries of Indian princes have probably been brought from Burma or from Badakshan, a locality for ruby, which has yet to be mentioned.
In Afghanistan permission to work the ruby mines near Jagdalak, thirty-two miles east of Kabul, has been obtainable from the Amir since 1870. The rubies found here lie in a micaceous crystalline limestone; many show a distinct crystalline form, which is identical with that of rubies from Burma. These stones were originally described as being spinel, but specimens, which have come to Europe, have been proved to be positively rubies. The occurrence of ruby in this locality is strikingly similar to its occurrence in Burma; as in Burma and Ceylon, so probably in Afghanistan also, spinel occurs associated with the ruby.
A ruby of 10 1/2 carats was brought to Europe by a traveler from Gandamak, a place about twenty miles from Jagdalak, and in latitude about 34° 20'0 N. and longitude 70° E. nothing further as to this occurrence is known, and it is possible that both place-names refer to the same occurrence.
Ruby mines in Badakshan in the upper Oxus R. (Scale, 1: 6,000,000)
The ruby mines of Badakshan were famous in olden times, and they supplied some of the vast store of treasure amassed by the Great Mogul. They are situated in Shignan, on the bend of the Oxus river, which is directed to the southwest, in latitude about 37° N. and longitude 71° 30' E. They lie between the upper course of the Oxus and its right tributary the Turt, near Gharan, a place the name of which signifies "mine", sixteen miles below the town of Barshar, in the lower, not the higher, mountain ranges. This locality is by no means a familiar one, and reports as to the mode of occurrence of the ruby here ware very conflicting. According to one they ware found in a white earth; according to another in red sandstone; while yet a third states them to be found in a magnesian limestone. From analogy with the Burmese occurrence, the last-named mode of occurrence seems the most probable. Rubies have been found formerly in these mines in large numbers, and associated with the variety of spinel known as "balas-ruby". Marco Polo, who visited the mines in the thirteenth century, states that the ruler of the country strictly limited the output from them in order to keep up the value. Part of the output was paid away as tribute to the Mongol Emperor, another part to other rulers, while the remainder was put into the market. The yield appears to have fallen off in later times, till in the end work was altogether discontinued. It is stated that the mines were reopened in the year 1866; whether they are being worked at the present day or not is unknown, but, according to a later report, they ware practically exhausted, and give employment to only few persons, the few stones that ware found being the property of the Amir of Afghanistan. A stone the size of a pigeon's egg have been found here in 1873.
It is possible that the rubies and spinels which have come into the market through Tashkent, and which, according to the merchants, were mined in the Tian-Shan Mountains, are in reality from these same mines. There is no reliable information as to the existence of ruby mines in the Tian-Shan Mountains or in Tibet, so that the 2,000 carat ruby received in late 19 century by Streeter, and said to be from Tibet, may also have been found in these mines on the Oxus. Compared with the importance of the occurrence of ruby in Asia, that in all other parts of the world is insignificant.
In Australia rubies of small size have been found in the gold-sands sometimes associated with the diamond, never, however, in large numbers. Such occurrences have been noted in the sands of Cudgegong River, in a few of its tributaries near Mudgee and at a few other places in New South Wales. In Victoria the gold-sands of Beechworth and Pakenham have yielded rubies. In all Australian ruby localities, however, this stone is very much less common than the sapphire. Moreover, red garnets have been mistaken for rubies time after time. Thus, many years ago, an abundant occurrence of rubies in the Macdonnell Ranges of the Northern Territory of South Australia was reported. No less than twenty-four companies were very shortly formed for the working of the deposits. A more thorough examination of the stones, however, showed them to be red garnets, of fine quality, but compared with the true ruby almost valueless. These same garnets are sometimes sold as" Adelaide rubies". The United States of North America yield a few rubies, occurring rarely associated with common corundum, which is very abundant in this country. In the Lucas mine on Corundum Hill in Macon County, North Carolina, small amounts of transparent red corundum, sometimes suitable for cutting, have been found. The boss of serpentine, which forms the main mass of Corundum Hill is traversed by large veins of common corundum. Rubies of much better quality have been found more in Cowee Creek, also in Macon County, about live miles from Franklin, and have been described (1899) by Professor J. W. Judd and Mr. W. E. Hidden. These authors point out that there are three distinct modes of occurrence of corundum in North Carolina and the adjoining States:
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