Psilomelane, hollandite, cryptomelane, coronadite, ramsdellite, pyrolusite and lithio-phorite were detected in a microscopic and x-ray study of material from four deposits in the Artillery Mountains area. The number of lines present in x-ray powder photographs of psilomelane from the area is quite variable. Ramsdellite occurs in both vein and bedded deposits and may have formed under diagenetic conditions in the latter. Soft wadlike material, which comprises the bulk of the manganiferous material in the bedded deposit examined, could not be identified but appears in general to be poorly crystallized, low in barium, high in strontium, and in some respects similar to cryptomelane, hollandite and psilomelane.

The origin of the manganese in the vein deposits studied is not clear, but several features suggest a hypogene origin. Field evidence favors a syngenetic sedimentary origin for the bedded deposit studied.

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