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<br />~ ~ <br />-2- <br />Field relations of these rock units are represented in Plate <br />II. General units mapped only. <br />Volcanic rocks consist principally of volcanic breccie, <br />latite, andesite, and basalt. Volcanic breccia is mostly <br />bleached white nearer to the surface and is often impregnated <br />with pinkish bentonite. An idealized mode of volcanic eruptions <br />is shown in Plate II, cross section A-A. Presence oP bentonite <br />indicates explosive igneous activity accompanied by election <br />of volcanic ashes. Upon settling and chemical alteration the <br />volcanic dust has resulted in the formation of the present <br />bentonite deposit. Presumably the explosive eruptions are of <br />local origin and areally limited. <br />E96NOMIC ASPECTS OF BEATTONITE <br />GENERAL CHARACTER <br />Bentonite, a soapy pinkish mineral which is partially <br />admixed with soil and volcanic rocks forms a discontinuous <br />mantle over the Pennsylvanian clastics. Impurities form s to <br />15 percent of the economic mineral. As inferred from the open <br />cuts developed on the claims, thickness of the bentonite layer <br />varies from I to 40 feet, the average being about 20 feet. <br />DISTRIBUTION <br />Bentonite appears to roughly encircle the monzonitic <br />intrusion and seems to encompass all of the Claims although <br />discontinuously. Variations in the thickness may be attributed <br />to inconsistent distribution of volcanic e~ectments, removal <br />of volcanic ashes by erosion, and original inequb~lities. <br />