Green hell in red world

ALLUVIAL EXPLORATION & MINING
PHOTOGEOLOGY | SEISMIC SURVEY | BANKA DRILLING | MANAGEMENT | TRAINING

Click to see a professional profile


GOLD
  gold
  gold chemistry
  gold transport
  gold production
Gold Geology
  alluvial deposits
  primary deposits
  gold maps
Gold History
  gold lore
  primitive
  classic
  medieval
  renaissance
  post-renaissance

DIAMONDS
  diamonds
  exploration
  diamond production
  diamond trade
  diamond value
  diamond wars
  diamond cutting
Diamonds History
  mining history
  large and famous
Diamond Pictures
  diamond pictures
Precious Stones
  rubies
  sapphires
  emeralds
  aquamarines
  gem cutting

ALLUVIAL EXPLORATION
  survey
BANKA Alluvial Drills
  drilling manual
  HAND drills
  drill parts
  tools 1
  tools 2
  tools 3
  tools 4
  MOTOR drills

ALLUVIAL MINING
example
Engines
DEUTZ engines
diesel-engines
Equipments
mining systems
gravel pumps
water pumps
high pressure
 water pumps

pump stands
couplings
engine-pump frames
Pipes, Hoses, etc.
water systems
Recovery systems
recovery systems
gold recovery
diamond recovery
River Dredges
diver-less dredges
Accessories
generators
firefighting pumps
Trucks 4x4
4x4 trucks
Spare Parts
parts
Pricing
Prices

SERVICES
photo geology
seismic survey
field manager
profile
photos
contact

PRECIOUS STONES

SAPPHIRE

VALUE

Sapphires of large size and fine quality are far more common than rubies of the same description hence the latter always command higher prices than the former. Thus a flawless carat sapphire of perfect transparency, velvety luster, and of a uniform deep cornflower-blue color, will seldom fetch more than $1,100, while $2,750 will be easily obtained for a ruby of corresponding size and quality. Sapphires of this description, weighing between 2 and 3 carats, are about equal in value to diamonds of good quality and of the same weight. Faulty stones, the color of which is pale or of irregular distribution, do not fetch more than a few shillings per carat. Since large sapphires are far more common than large rubies, there is a much smaller disproportion between the prices of large and of small sapphires than between those of large and small rubies. In the case of sapphires, indeed, the prices are almost proportional to the weight, a stone of double the weight being not much more than double the value, and so on. The flaws seen most commonly in sapphire are in general the same as in ruby, namely, clouds, milky and semi-transparent patches, white glassy streaks, alternation of differently colored layers, areas showing silky luster, etc.

Some few sapphires of exceptional beauty and size have acquired wide renown. The most magnificent of these is one of 951 carats seen in 1827 in the treasury of the King of Ava, as described by the English Ambassador at the Court of that monarch. It is reported to have been found in Burma, and to be not absolutely flawless. In the collection of the Jardin des Plantes in Paris was a rough stone of 132 1/16 carats; this is the "wooden spoon seller's" stone, and is said to have been found in Bengal by a man who followed that particular trade. It is known also as the "Rospoli" sapphire, after the family in whose possession it formerly was, and is one of the most magnificent of blue sapphires, free from all patches and faults. In the same collection was preserved another fine sapphire, 2 inches long and 1 1/2 inches wide. A beautiful sapphire, weighing over 100 carats, was the property of the Duke of Devonshire; the lower portion of this stone is step-cut while the upper is cut as a brilliant. Among other noted sapphires may be mentioned a dark, inky, faultless stone weighing 252 carats, which was exhibited in London in 1862, and a fine blue stone, with a yellow patch on one side, which weighed 225 carats, and was exhibited in Paris in 1867.

OCCURRENCE

The mode of occurrence of sapphire is practically the same as that of ruby. It is found in sands and in solid rock, frequently together with ruby, in the manner already described. There is probably no single locality where one stone is found without the other; they are invariably associated together, here one and there the other predominating, and with them are usually found other varieties of precious and common corundum. Ruby predominates at the localities especially described above for this gem. Sapphire is the more abundant of the two in Siam (the two, however, coming from different mines), in Ceylon, at Zanskar in Kashmir, in the gold and diamond sands of Australia, especially of New South Wales, and in Montana in the United States. Other localities, such, for example, as the European, are unimportant. By far the largest numbers of sapphires, which come into the market, are from Siam, the production of other countries being in comparison with this quite insignificant.

Not only the largest numbers of sapphires, but also the finest quality of stones, come from Siam.

Map of Burma and Siam

Map of occurrence of ruby and sapphire in Burma and Siam.
(Scale, 1:15,000,000.)

The most important of the long known mines of this country, the systematic working of which has later been undertaken by Europeans, are those of Hattambang, in which a few rubies are found with the sapphires. A certain number of good stones are found in the ruby mines of Chantabun and Krat, mentioned above. It is estimated that the mines of Ho Pie Rin in Hattamballg alone yield five-eighths of the total sapphire production of the world. Many of the stones found here surpass those from all other localities in their intense blue color and velvety luster. Many, however, of the so-called inky stones, are so deep in color that in reflected light they appear almost black. It is a remarkable fact that the larger stones exceeding one carat in weight are almost invariably of finer color and quality than smaller stones. Although the occurrence of sapphire in Siam was known at least as early as the beginning of the nineteenth century, the mines have been regularly worked only since about the year 1875. It is possible, however, that stones from these mines came into the market through Burma and were sold as Burmese stones. The mines of Siam have, therefore, grown into importance with great rapidity. According to Streeter, to whom the present account is due, the sale of Siamese sapphires by a single firm of London gem merchant amounted, in 1889, to £75,000 ($8,150,000).

The sapphire in this locality is found in slightly sandy clay, usually about 2 feet below the surface of the ground. The most important mines are situated in the sides and floor of the Phelin valley. Each is a rough pit almost 4 feet square and 5 to 12 feet deep. As usual in occurrences of this type, the clay is washed away from the excavated mass and the stones picked out of the sandy residue.

So far as is known at present, the sapphire-bearing deposit extends over an area of about 100 square mi1es. The center of the trade both for rubies and sapphires is the town of Chantabun, on the Gulf of Siam, in latitude about 12° 30' 0 N. In the neighborhood of this town, besides the ruby mines already mentioned, there are deposits in which sapphire is the predominating gem, and these appear to have been known and worked longer than those of Battambang. The sapphire has not yet been observed to occur in Siam in deposits of any type other than gem-sands, so that little is known of the minerals associated with it in the mother-rock. As to the occurrence of sapphire in Burma, there is little to be added to what has been already said respecting the occurrence of ruby in this country. Sapphires are found at the same localities and under the same conditions, but where one sapphire is found there will be 500 rubies. While, however, rubies of good quality and exceeding 10 carats in weight are of extremely rare occurrence, large sapphires are found with considerable frequency. The discovery of sapphires weighing 1988, 951, 820, and 253 carats respectively, has been reported. Stones weighing 6 to 9 carats, though common, are often faulty. The largest faultless stone yet found in Burma weighs 79 1/2 carats; all others show considerable faults. The color of Burmese sapphires is usually so dark that they appear almost black, they are seldom comparable in quality with those from Siam, and do not command a high price. The sapphire occurs in Ceylon associated with many other precious stones. The yield of gems of this island is not large, the total value of the annual production being said to be no more than £10,000 ($1,086,000). The locality is, however, remarkable for its variety of gem stones, namely, sapphire, ruby, topaz, amethyst, cat's-eye and other varieties of quartz, garnet (almandine and cinnamon-stone), zircon (hyacinth), chrysoberyl in its different varieties, spinel, tourmaline, moon-stone, and others which are rarer and of less importance. In association with the precious stones, there are found fragments of common corundum, magnetite, feldspar, calcite, etc. Of the above-mentioned precious stones the sapphire is by far the most frequent.

The precious stones and the minerals with which they are associated were originally, for the most part, constituents of certain granite and gneissic rocks, by the weathering and disintegration of which they have been set free. While the sapphire and garnet were original1y embedded in gneiss, other precious stones, such as the ruby and spinel, have been derived from the crystalline limestones (marbles), which are associated with the gneiss. The gems occur in their mother-rocks only sparingly, and are never obtained directly from them, but from the sands, gravels, and clays formed by weathering. These secondary deposits, in which the gems weathered out of the solid rock have been accumulating for long periods of time, are found in the beds of the streams of the present day, and on the sides of the hills above the present high-water level.

The richest locality for gems is in the south of the island, on the southern slopes of the mountains in the Saffragam district. On this account the principal town of the district has received the name of Ratnapura (or Anarhadnapura), which signifies the "City of Rubies". The occurrence of gems is, however, by no means confined to this one locality, st0nes being found in the western plain between Adam's Peak and the sea, near Neuraellia, Kandy, Matella, and Ruanwplli and in the riverbed of the Kalany Ganga near Sittawake, six miles east of Colombo. Also near Matura, on the south coast of the island, and in the rivers on the east in the neighborhood of the Mohagam River. The localities especially rich in sapphires are the Saffragam district and the neighborhood of Matura, where a considerable number of stones of large size and fine quality are found.

The gem mines near Ratnapura were visited and described by Ferdinand Hochstetter, during the voyage of the Austrian frigate Novara. They are situated on the Kalu Sella, a small tributary of the Ralu Ganga, partly in the bed and partly on the right bank of the river. The mines, which reach a depth of 30 feet, were not being worked at the time of Hochstetter's visit, and were filled with water. The uppermost layer is thick yellow clay with nodules of limonite resembling our boulder clay in appearance. Below lies unctuous black clay and dray sand; then bituminous clay enclosing abundant plant remains, the teeth and bones of elephants, etc, then sand, and finally a bed of pebbles with red, yellow, or sometimes blue clay. This constitutes the gem layer, and is known as the stone-gravel or "malave". The gems are found mainly between the large pebbles; they are especially abundant when the layer contains greenish, talcose, partly decomposed mica. In the Kalu Ganga, between Ratnapura and Caltura, most of the gems are washed from the sands above small rapids in the river. The gem mines of Ukkette Demy, near Ratnapura, were visited in 1889 by J. Walther, of Jena, who furnished the following details: The mines lie in a valley basin about 3 kilometers wide, in which several side streams deposit the debris weathered from the surrounding ancient crystalline rocks, such as gneisses, etc. The strata in which the mines are sunk include an upper layer of 80 centimeters of mud, then 50 centimeters of white sand, with a few bands of black vegetable matter; beneath this a meter of dark yellow clay, and then the gem layer consisting of a tough clay, which may be white, yellow, red, or green, and encloses much-decomposed boulders of the surrounding crystalline rocks. The gem-bearing clay, which rests on a bed of gravel 3 meters thick, is richest when white and poorest when green. The precious stones have doubtless been derived from the gneisses, etc., of the neighborhood, since grains of sapphire have frequently been found in decomposed boulders of these rocks contained in the deposit.

The sapphires of Ceylon are not of very good quality; though a few stones of a rich color are found, the majorities are too pale to be of any great value. Star-sapphires are not of unusual occurrence, and yellow ("oriental topaz") and white (leuco-sapphire) stones are abundant, while partly-colored sapphires are not infrequently met with. The original crystalline form of some stones is distinctly recognizable, although the edges are usually not quite sharp; others are much worn and rounded. Large stones are rarely found here, and the ruby is far less abundant than the sapphire.

Another important locality at which, since 1881 or 1882 sapphires in large numbers have been found, is the Zanskar range of Kashmir, in the northwest Himalayas. The exact locality of these finds was for a long time a secret, which was jealously guarded, especially from Europeans, first by the original discoverers and then by the Government of Kashmir. The first geologist who succeeded in visiting the locality was Mr. T. H. D. LaTouche, of the Indian Geological Survey.

[ RUBY  1  2  3  4  5  SAPPHIRE  7  8  9  EMERALD  11  12  13  AQUAMARINE  15  ]
Diamond   Diamond Geology and Mining   Diamond Trade


Related links:
Recomend this page:


Seismic Survey 


Rafal Swiecki, geological engineer email contact

This document is in the public domain.

March, 2011