From foreword: This bulletin is the second of the series "Contributions to Geochemistry" which was begun in 1946 with Bulletin 950, "Contributions to Geochemistry, 1942-45". This series is the successor to earlier ones, also published as U. S. Geological Survey Bulletins, "Report of work done in the Division of Chemistry and Physics" (1879-1893), "Contributions to chemistry and mineralogy from the laboratory of the United States Geological Survey" (1900), "Contributions to mineralogy from the United States Geological Survey" (1905), and "Mineralogical Notes" (1911-16).

From abstract: Gypsum-bearing rocks crop out in Gypsum and Yellow Jacket Gulches, on Sheep Mountain, which is about 90 miles northeast of Anchorage, Alaska. The gypsiferous rock occurs in deposits of irregular shape in the greenstone. Both the gypsiferous rock and the greenstone are hydrothermal alteration products of the volcanic rocks of Jurassic age which comprise the bulk of the mountain. Near-surface samples of the gypsiferous rock contained an average of 25 to 30 percent gypsum ; some contained as much as 50 percent. Quartz, alunite, clay, sericite, and pyrite are contaminating constituents of the ore. Six of the largest and most accessible of the gypsum deposits were mapped and calculations show that three of the deposits contain an aggregate of approximately 311,000 short tons of indicated gypsiferous rock and four of the deposits contain 348,000 short tons of inferred gypsiferous rock.