Contact mine, Chief Mining District, Lincoln County, Nevada, USAi

Regional Level Types
Contact mine	Mine
Chief Mining District	Mining District
Lincoln County	County
Nevada	State
USA	Country

Sec 18 T3S R67E
Alteration: Silicification

Commodity: Ore minerals not given in the literature

Deposit: Ore consists of Fe-stained brecciated quartzite cemented with coarse-grained calcite. Burt vein occurs in quartzite. Lenses of soft red iron oxide occur.

Development: No activity at time of examination in 1983, but trenching had been done in the last 10 years.

Geology: Contact vein along fault contact between the quartzite & carbonates. Carbonates contain lenses of iron oxide. Burt vein strikes N 45 W and 65 s W in the quartzite. Sample from contact adit consisted of dark brown jaspery gossan and silicified (recrystallized) quartzite from the dump. In the area of the shafts the dominant rock type is a fine-to medium-grained tan-purple quartzite, dolomite or limestone, altered to a punky mixture of clay and iron oxides, also exposed along portions of the trenches. The trenches follow a highly iron-stained brecciated zone 10-20 ft wide striking n45e,dipping steeply se. This zone contains brown and red siliceous (or jaspery) Fe-rich pods and lenses. At S end of trench, altered limestone is exposed which contains pods and veins of grey calcite. Limestone and quartzite are evidently juxtaposed by thrusting at this site, As they are in other parts of the district, but here the units are also juxtaposed along several high-angle structures. Some bright red-orange oxides coat quartzite fault breccia (cemented by Fe and silica) found in the trench. The vein explored by the contact adit and shafts follows a fault zone which is undulatory, but generally n-s striking. Sample from contact adit consisted of dark brown jaspery gossan and silicified (recrystallized) quartzite from the dump. In the area of the shafts the dominant rock type is a fine-to medium-grained tan-purple quartzite, dolomite or limestone, altered to a punky mixture of clay and iron oxides, also exposed along portions of the trenches. The trenches follo W a highly iron-stained brecciated zone 10-20 ft wide striking n45e, dipping steeply se. This zone contains brown and red siliceous (or jaspery) Fe-rich pods and lenses. At S end of trench, altered limestone is exposed which contains pods and veins of grey calcite. Limestone and quartzite are evidently juxtaposed by thrusting at this site, As they are in other parts of the district, but here the units are also juxtaposed along several high-angle structures. Some bright red-orange oxides coat quartzite fault breccia (cemented by Fe and silica) found in the trench. The vein explored by the contact adit and shafts follows a fault zone which is undulatory, but generally n-s striking.

Ore(s): Fault Contact

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Link to USGS MRDS:	10037351

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References