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fitted it for this use. A layer, the bottom of which was 3 or 4 feet above the underlying shale, proved to be the best, that which is of strictly first-class quality having been yet found only in this quarry. He has used for this purpose about 250 blocks ranging in diameter from 4 to 5 feet and in thickness from 14 to 18 inches, and has sold to others about 30 such blocks. These blocks he values at from one to two dollars per cubic foot. In his mills at Akron he is now using 28 runs of these stones, and producing 80,000 barrels of oatmeal and 50,000 barrels of pearl barley per annum. The stones used for pearling barley are placed upright in iron shells revolving slowly in a direction opposite to that of the stone. Mr. Shumacher is now putting the machinery into a new mill, which will increase the annual production of oatmeal to 240,000 barrels, of the value of $1,500,000.

The success of this industry is largely the result of the peculiar character of a small part of the stone from this quarry. The work was com menced in 1856, and has steadily increased until the present time. Its dependence upon the character of this rock, in the estimation of Mr. Shumacher, is indicated by the fact that he has purchased the entire quarry and is now putting it in shape for a large production of building stone, expecting, as this is removed, to uncover and make available a full supply of that which is especially fitted for milling purposes.

GRINDSTONES.

The principal source of material for grindstones is the sandstone of Ohio, very largely that formation known as the Amherst stone or Berea grit (described in the foregoing section), and also from the neighborhood of Lake Huron, Independence, and Minetta. The principal center of manufacture is Cleveland, Ohio. The production during the year 1882 is estimated at about 50,000 tons, valued at $700,000.

Our exports, which are of considerable amount, are mainly to the West Indies, Central America, South America, and Mexico.

Grindstones are imported to a small extent, mainly from England and Nova Scotia.

INFUSORIAL EARTH.

One variety of infusorial earth, containing over 80 per cent. silica in a finely comminuted state, is found in Nevada, and has been placed on the market as a polishing powder under the name of electro-silicon. Its composition, as determined by Mr. W. Habirshaw, is:

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This substance is remarkably fine, and free from coarse grit. It has

no use except as a polishing powder, and the company working it report that it could not be sold for any other purposes for the cost of freight. For the special purpose for which it is utilized, however, it serves excellently. The method of manufacturing a merchantable article is simply to pulverize the crude mineral, the particles of which are loosely adherent. The amount utilized for making electro-silicon in 1882 was derived chiefly from a stock which had been mined in previous years.

Infusorial earth of a different character and texture from that used as electro-silicon is found in Nevada; and there are large deposits in Los Angeles county, California, which have been utilized to a small extent in furnishing a polishing powder. This substance is often mistaken by prospectors for kaolin.

At one time infusorial earth imported from Gemany was used to a considerable extent in California in the manufacture of giant powder. The mineral found in California and Nevada did not possess sufficient absorbent powers, although it was tested for this purpose. Latterly, however, infusorial earth of all kinds has been supplanted in the manufacture of giant powder at the California works by wood pulp brought from the Eastern States.

Besides its use as a polishing powder, infusorial earth is sometimes used to give "body" to soap.

PUMICE-STONE.

Nearly all the pumice used in this country is imported in the lump from Italy, where it is found in the neighborhood of Mount Vesuvius, and is ground here the only exception being small lots of California pumice-stone which have reached the market from time to time. There are abundant deposits of pumice-stone at Lake Honda, San Francisco county, California; also at Little Owens lake and other localities in Inyo county in the same State. It is of good quality. Whittier, Fuller & Co., of San Francisco, own the Lake Honda deposits, and manufacture from 60 to 70 tons per year, supplying the market on the coast for the most part. A portion of the pumice used on the Pacific coast is imported stone, prepared in New York. Formerly all that was used there was imported, but now two-thirds of what is consumed is made in San Francisco, the above-named firm being the only manufacturers. The Italian sells at $25 per ton in New York City. During the fiscal year 1882 the imports amounted to $29,019 and the exports to $2,423. Pumice-stone is chiefly used in polishing marble.

CARBONS.

Borts, black diamonds, carbons, or carbonados, as the black variety of the diamond is variously called, are used more and more extensively in the arts every year. This substance is employed largely in diamond

drills used in mining and for machinery designed to saw, cut, and dress various refractory substances. It consists of pure carbon excepting from 0.27 to 2.07 per cent. The specific gravity ranges from 3.012 to 3.416. In size, shape, and temper, very great differences exist. Pieces from 400 to 700 karats have been found. The supplies used in this country come from the province of Bahia in Brazil. Carbons have also been reported to occur in South Africa, India, and Russia, but these occurrences have not been authenticated.

Very frequently discoveries of carbons are reported to have been made in the United States, but the supposed black diamond is commonly found to be titanic iron, easily crushed to dust by means of a light hammer or by strong pliers. Inquiries addressed to dealers and experts failed to develop any authentic occurrences.

The price of carbons has advanced during the past three years from $3 to the present rate of $15 to $20 per karat, a price so high as to almost stop the use of this important mineral except in very special cases. 31 M R

PRECIOUS STONES.

Domestic production.-Although so many varieties of gem stones are known to occur in the United States, many of which afford fine specimens, while a few valuable stones are exclusively indigenous, the annual output is still very small in comparison with the prospective extent of the field. It is impossible to obtain exact statistics of the product, but an extensive correspondence with experts and dealers justifies an estimate of between $50,000 and $60,000 as the sales in 1882 of cut gem stones of domestic production, exclusive of the gold quartz souvenirs, which should be credited to precious metal mining. The value of the stones before cutting was much less-probably little above $10,000, as about four-fifths of the market value of the stones represents the enhancement due to cutting. This applies more strictly to the common gem stones; and in the case of agates and moss-agates the value of the uncut stones is often not one per cent. of the price of the gems after cutting. The amount stated as the value of uncut stones is of those sold to be cut; besides which, as shown in the accompanying paper by Mr. Kunz, there are sales of small amounts, to tourists and collectors, of stones which are valued merely as specimens, and which do not reach the gem market.

Few persons are familiar with the appearance of gem stones in their native state; so that while quartz pebbles are often mistaken for rough diamonds, garnets for rubies, ilmenite for black diamonds, etc., on the other hand it is quite probable that many valuable occurrences have escaped notice. The competition of the cheap foreign cutting is also a disadvantageous factor.

Imports and re-exports.-The following tables show the values of foreign stones imported and re-exported during a series of years. They probably include small quantities of American stones, as these are sometimes cut in Europe and thus lose their identity.

Precious stones imported into the United States during the fiscal years specified (specie values).

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1880

1881

1882

Calendar year 1882.

Values.

$6,698, 488

8, 332, 511 8,444, 525

8, 154, 397

Precious stones of foreign production exported from the United States during the fiscal years

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An annual importation of $8,000,000 worth of precious stones (to say nothing of the considerable quantities smuggled, which escape the record), shows that this country is an exceptionally heavy purchaseras would be supposed even in the absence of statistics. The imports vary greatly in different periods and are largely determined, as may be seen by a comparison of the years cited, by changes in the general prosperity or by speculative profits. The new tariff law fixes the duty on precious stones of all kinds at 10 per centum ad valorem.

AMERICAN GEMS AND PRECIOUS STONES. (a)

BY GEO. F. KUNZ.

In the United States, systematic mining for gems and precious stones is being carried on at only two places, viz., Paris, Maine, and Stony Point, North Carolina. In other cases where gems are found they are either met with accidentally, or occur in connection with other materials that are being mined, or in small veins which are only occasionally met with. They are often gathered with little system on the surface, as is the case with the sapphire, garnet, and olivine found in Montana and New Mexico; or from the beds of streams and decomposing rock, as

a This paper is the result of an application by Mr. Williams to Messrs. Tiffany & Co., of New York City, for the purpose of obtaining certain facts relative to the gems and precious stones of the United States. I may here state that whatever information is presented is due to the usual courtesy and generosity of that firm, whenever they can assist in advancing science or art, in placing at my disposal not only all the facts and material at their command, but also the time required by me in collecting whatever other existing data there might be relative to this subject. In view of the little that has been published and the paucity of reliable facts, it is hoped that the deficiencies in this article may be overlooked.-G. F. K.

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