CHISTOCHINA DISTRICT
The Chistochina district is in the northwest part of the Copper River basin near the intersection of lat 63°00' N. and long 145°00' W. The drainage area of the Chistochina River, including the southern foothills of the Alaska Range, roughly determines the boundaries of this district.
The initial gold discoveries of the Copper River region were made in this district along the Chisna River in 1898 by Hazelet and Meals (Moffit, 1944, p. 27). Slate Creek and Miller Gulch later became the leading gold-producing areas. Production from this district began in 1900 and continued, though at a diminishing rate in the later years, to 1942. From 1942 to 1959 the district was almost dormant, with only sporadic small-scale activity. Total production from 1900 through 1959 was about 141,000 ounces, all from placers. Production data from 1931 through 1945 are not complete.
Bedrock in the district consists of Carboniferous and Permian clastic and sedimentary rocks - predominantly shale, limestone, conglomerate and some sandstone - and subordinate volcanic tuffs and lava flows. All the foregoing rocks are cut by dikes (Moffit, 1944, p. 28). The gold placers were formed by reworking of glacial debris and occur in bench gravels as well as present stream gravels.
NIZINA DISTRICT
The Nizina district is in the eastern part of the Copper River drainage basin between lat 61°12' and 61°37' N. and long 142°22' and 143°00/ W. This is a placer district along the Nizina River, a tributary of the Chitina River.
In 1898-99 prospectors were active in the Chitina River valley and some went up as far as the Nizina area. Although copper deposits were soon found and quickly developed, it was not until 1902 that placers rich enough to precipitate a rush were found on Chititu Creek (Moffit and Capps, 1911, p. 76). The rich deposits were quickly exhausted and the operators who remained developed previously known lower grade gravels on Chititu and Dan Creeks. In 1959 these gravels were still being mined, although on a smaller scale. Total production through 1959 from the Nizina district was 143,500 ounces of gold; all but about 60 ounces was from the placers.
The geology of the Nizina district was described by Moffit and Capps (1911, p. 20-75). Bedrock in the mountain areas consists for the most part of moderately folded Permian and Triassic(?) marine sediments and greenstone intruded by laccoliths, dikes, and sills of quartz diorite porphyry (E. H. Cobb, written commun., 1962). Deposits of mor-raine and alluvium blanket the lower slopes of the mountains and fill the river basins. The source of the gold in the placers is probably the small quartz veinlets in the black shales that may be related to porphyritic intrusives in the shales. High bench gravels, remnants of a deep alluvial valley fill, contain workable deposits, but the richest placers are in present stream gravels where the gold has been concentrated by reworking of older deposits (Moffit and Capps, 1911, p. 98-100).
