Boulder Creek

Prospect, Inactive

Alternative names

Claus Rodine

Commodities and mineralogy

Main commodities As; Sb
Other commodities Au; Pb; W
Ore minerals arsenopyrite; galena; gold; scheelite; stibnite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-2
Latitude 64.6505
Longitude -165.518
Nearby scientific data Find additional scientific data near this location
Location and accuracy Boulder Creek is a west tributary to Snake River; it flows east from headwaters in the eastern Nome C-2 quadrangle. The prospect is on the south side of Boulder Creek, approximately at the elevation of a prominent ditch and about 1,100 feet above the confluence of Twin Mountain Creek (shown as Twin Mtn Ck on the map) and Boulder Creek (Mertie, 1918 [B 662-I, p. 425-449]). The location is within a mineralized area mostly above the Boulder Creek prospect. It is accurate within about 1,000 feet. Locality 37 (Boulder lode) of Cobb (1972 [MF 463], 1978 [OFR 78-93]), is nearly coincident with some quartz veins but it is about one-half mile downstream from this prospect.

Geologic setting

Geologic description

The Boulder Creek or Claus Rodine prospect is a complex deposit related generally to the Rodine fault (Bundtzen and others, 1994). The prospect was first reported by Mertie (1918 [B 662-I, p. 427-429]), who noted that a 50-pound pod of stibnite had been mined from a pit near the adit and that quartz in the adit locally contained crystalline scheelite. Cathcart (1922, p. 252) also visited the prospect and reported quartz veins with pyrite and arsenopyrite associated with extensive sulfidation of schist.
The deposit was relocated by Kennecott Exploration Company in about 1991, and although the adit was reopened, it was too dangerous for underground work. The prospect was within the area of a large Kennecott soil geochemistry survey, and two trenches were cut above and parallel to a placer ditch, at right angles to the Rodine fault. The soil geochemistry survey shows that the Boulder Creek area is highly anomalous in arsenic and antimony, but only moderately anomalous in gold. Values in soil approaching the Rodine fault are as much as 3,100 ppm arsenic and 190 ppm antimony. The maximum amount of gold in a soil was 76 ppb. Rock samples collected along the trench system locally exceed 10,000 ppm arsenic and contain as much as 0.03 ounce of gold per ton.
At the prospect, the Rodine fault juxtaposes marble to the west against mica-schist; most of the mineralization, extending for as much as 100 feet east of the fault, is in schist. Rubble above the prospect is locally composed of ankeritic marble with some quartz. The country rock schist on the east side of the Rodine fault was mapped by Bundtzen and others (1994) as calcareous metaturbidite schist, a unit inferred to be relatively old and to lie near the base of the section along the Twin Mountain antiform.
Geologic map unit (-165.520609337785, 64.649732922324)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Mid-Cretaceous; postdates regional metmorphism and is probably similar in age to other low-sulfide Au-quartz veins of the Nome district (see, for example, the Divide prospect, NM058).
Alteration of deposit Sulfidation of schist and ankeritization of marble.

Production and reserves

Workings or exploration An adit had been driven about 87 feet when the prospect was visited by Mertie in 1916; it was subsequently extended a few more feet. The prospect had power from a small Pelton wheel that was still at the site in 1995. A large soil geochemistry survey was completed and about 600 feet of trenches were cut in 1992 or 1993 by Kennecott Exploration Company.
Indication of production None
Production notes A small amout of high-grade stibnite ore may have been mined.