Show production OF GRINDING PEBBLES A falling off in the production of pebbles and liners for use in tube mills as shown by final figures for 1918 compiled by the united states geological survey department of the interior reflects both uncertainty of market and changes in grinding Irac practice tice grinding pebbles natural pebbles for grinding rock ores minerals cement clinker and many other materials were obtained in 1918 as in preceding years from the beaches between oceanside and encinitas Enci san diego county calif according to reports received by the survey the entire output was marketed by robert burns co oceanside the pacific coast pebble co encinitas Enci and thebo encinitas Enci the production of these pebbles in 1918 was considerably smaller than in 1917 probably in large part because the growing use of steel balls is supplementing the use of pebbles but the decrease was due in part to the uncertainty of the market which deterred pickers from collecting I 1 and sorting stocks that they might have marketed the output of artificial pebbles in 1918 was considerably greater than in previous years these so called artificial pebbles are either roughly cubical or mechanically smoothed and rounded blocks of quartzite manufactured by the jasper stone co sioux city iowa or mechanically smoothed and rounded blocks of or rhyolite manufactured by omer marls maris manhattan nev in 1918 the sales of pe pebbles abbles and of cubes and artificially rounded blocks for use in grinding amounted to tons valued at this was a decrease roughly of 2300 short tons or nearly 20 per cent compared with the sales in 1917 the value however shows an increase of nearly 24 1000 or about 30 per cent compared with that for 1917 besides this marketed output there was an indeterminable consumption probably large of substitutes for grinding pebbles by mills which used local pebbles boulders lumps of ore or native rocks only estimates are available to show the quantities of flint pebbles imported the records of the bureau of foreign and domestic commerce indicate that the quantity of grinding pebbles imported in 1918 was probably a little over short tons about 70 per cent of which came from denmark and the remainder from france the total new supply of grinding pebbles contributed to domestic markets in 1918 appears thus to have been about short tons as compared with approximately tons in 1917 tons in 1916 and tons in 1915 this diminishing supply is evidence of the growing use of steel balls or other substitutes for grinding pebbles tube mill liners the domestic output of flinter flint or quartzite tube mill lining in 1918 was 2535 short tons valued at compared with short tons valued at in 1917 in 1918 there were only two producers the american flint company iron city tenn and the jasper stone company sioux city iowa |