Transactions . Breccia of Dolomite and Sandstone Cemented with Dolomite Spar, Quartz andSphalerite. Red Cloud Mine. (One-half the natural size.) also with the veins and brecciated deposits. They are of butlittle economic importance, except when they occur in or adja-cent to the beds of disseminated ore or convenient to the otherand larger ore-bodies. These small veinlets appear to have Fig. Splialtrite Cavities in Dolomite Filled with Quartz and Sphalerite. (Natural size.) originated by the deposition of the ore in fractures, howeverproduced. Some of these cavities appear to have been cau
Transactions . Breccia of Dolomite and Sandstone Cemented with Dolomite Spar, Quartz andSphalerite. Red Cloud Mine. (One-half the natural size.) also with the veins and brecciated deposits. They are of butlittle economic importance, except when they occur in or adja-cent to the beds of disseminated ore or convenient to the otherand larger ore-bodies. These small veinlets appear to have Fig. Splialtrite Cavities in Dolomite Filled with Quartz and Sphalerite. (Natural size.) originated by the deposition of the ore in fractures, howeverproduced. Some of these cavities appear to have been causedby shrinkage (Fig. 27), perhaps due to the dolomitization ofthe beds in which they occur; others seem to have been 592 THE ZINC-AND LEAD-DEPOSITS OF NORTB ARKANSAS. Fig. 28. formed by the dissolving out of the rock along joints and bed-ding-planes. (Fig. 28.) 3. Alteration-Products. The alteration-products of the region offer nothing new orunusual. They consist chiefly of smithsonite and calamine, but the so-called tallow-clay, described below, is worthy ofmention in this connection. Where lead-ores prevail, there isusually more or less anglesite, cerussite and pyromorphite. III. The Relations of the Geologic Structure to the Ore-Bodies. 1. The Bedded Ores. It has already been pointed out that the ore-bodies of Ar-kansas are partly contemporaneous with, and partly newer than, the rock
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
