GEMSTONE MINING
Aside from the highly mechanized and efficient diamond-mining meth¬ods used in Africa, most gemstones are recovered from small pits sunk in gem-bearing gravel deposits or from short tunnels and shafts in hard rock. While extensive gem-bearing gravels containing rubies, sapphires, spinels, and other splendid gemstones occur in Ceylon and Burma, large quantities of topsoil and sterile gravel must be excavated before the layers containing gems are uncovered. After a pit is sunk with much labor and cost, the operators cannot be certain that they will find a productive deposit underneath.

Many years ago it occurred to someone to try to mechanically mine, wash, and sort the gem-bearing gravels of the Mogok district in Burma under the reasonable assumption that mod¬ern methods and machinery could surely take the place of the traditional native labor and make mining far more efficient and profitable. Accord¬ingly, the Burma Ruby Mines, Ltd. was organized and set in operation, but after some years of successful operation it was forced to dissolve in die face of vanishing profits. Gem mining in Burma is now back to the unmechanized state where it started and where it will probably remain for many years to come. In Ceylon, mechanical recovery and washing of gravels has never been tried extensively, due partly to the attitude of the people, who prefer that their native gemstone resources be exploited slowly over a period of many years instead of all at once. Naturally this Drevents oversupply problems and assures that the miners will have gemstone resources to mine for generations.

A special kind of gemstone deposit is known as a pegmatite, or a very coarse-grained mass of quartz and feldspar usually occurring as a vein¬like body enclosed in the country rock. Practically all aquamarines, morganites, topazes and tourmalines come from “pockets” or cavities in pegmatites, especially from those in Brazil, Madagascar, and California. Unfortunately, these gem-bearing deposits are not extensive as a rule, some being merely a few feet thick and containing only one or two pro¬ductive pockets in which the crystals are of gem quality. Sometimes a pegmatite yielding good gemstones is exhausted in a few months, and the miners must abandon the deposit and search for another which shows signs of promising mineralization. Unfortunately, there is no way of being certain that gem-bearing pockets exist in a pegmatite unless the gemstones actually appear in the outcrop. Unless better means are found to detect the presence of gemstones beneath the surface, pegmatite gemstones will become increasingly scarce and more expensive. Many of the famous pegmatites of Brazil, Madagascar, and California are now exhausted, with fewer and fewer new finds being made every year.

In those mines where gemstones persist in depth, notably in the “pipe” diamond deposits of Africa, costs of mining steadily increase with depth, as is true of any underground mine. Only by the exercise of ingenuity in developing more efficient methods of mining has the De Beers Syndi¬cate been able to provide diamonds at reasonable cost. Even so, costs in this area are rising as rapidly as they are in other segments of the econ¬omy and have been reflected in the recently imposed price rises for rough diamonds.

Mining for gemstones is, at best, a precarious business. Deposits are small, returns uncertain, and often profits so meager that discouraged miners leave the fields to enter other pursuits. While the gemstones them¬selves are “free” for the taking, it can be readily appreciated that all of the easily available deposits have long since been skimmed off, leaving those whose exploitation is possible only at considerable cost. In the long run, we may be certain that natural gemstones will become increasingly scarce and more costly.