GRADE AND TONNAGE MODEL OF POLYMETALLIC VEINS

By James D. Bliss and Dennis P. Cox

COMMENTS The data used to generate grade and tonnage models for polymetallic veins reflect considerable complexity in the geology and economic conditions under which deposits are produced or evaluated. This model represents a first attempt to resolve these complexities. Four important factors may affect the adequacy of this model.

1. Zinc grades are subject to considerable uncertainty because smelters have in the past penalized producers for ore containing zinc which in turn caused mine operators to avoid zinc-bearing ore in their mining and milling. Zinc grades are likely underestimated. Irregular behavior in the zinc-grade model may be due to these factors.

2. Polymetallic veins of two types appear to exist--a base-metal polymetallic vein worked primarily for a base metal or metals and silver and a gold-silver polymetallic vein with copper, lead, and zinc production likely in less than half the deposits. Grade and tonnage models are presented for the base-metal polymetallic veins. Grade and tonnge models are not presented for the gold-silver polymetallic veins because preliminary data are inadequate. In our data, districts in which both types occur generally have six times as many base-metal polymetallic veins as gold-silver polymetallic veins.

3. The Slocan Mining District, British Columbia, Canada, contributed nearly 60 percent of the deposit data for the base-metal polymetallic veins, and this may bias the models in ways not identified.

4. Deposits are defined as all workings within 1 km of each other and having a minimum of 100 tonnes of ore. A few deposits are for districts with workings of unknown spacing. See figs. 90-94.

Figure 90. Tonnages of polymetallic vein deposits.

Figure 91. Silver grades of polymetallic vein deposits.

Figure 92. Gold grades of polymetallic vein deposits.

Figure 93. Lead grades of polymetallic vein deposits.

Figure 94. Zinc and copper grades of polymetallic vein deposits. A, Zinc. B, Copper.

Name Country

Albert Lea Group USAZ

Altoona-Elkhor-Mercury CNBC

Amazon USMT

Antoine CNBC

Arlington CNBC

Badger USAZ

Baltic and Revenue USCO

Baltimore USMT

Bell CNBC

Bell and California USCO

Bell Boy-Niles-Towsley USMT

Big Four USMT

Bosum CNBC

Bullion USCO

C.O.D. USAZ

California-Hartney-Marion CNBC

Carnation-Jennie Lind CNBC

Central Cerbat District USAZ

Champion-New London USAZ

Chlorite District USAZ

Comstock CNBC

Cork-Province CNBC

Dardanelles CNBC

Defiance USAZ

Eva May USMT

Fisher Maiden Group CNBC

Flint-Martin CNBC

Galena Farm and vicinity CNBC

Gray Eagle USMT

Idaho-Alamo Group CNBC

Idaho-Alamo-Silver Bell CNBC

Ivanhoe-Canadian CNBC

Keno Hill-Galena Hill CNYT

King Solomon USMT

Leadsmith CNBC

Legal Tender USMT

Little Nell USMT

Liverpool USMT

Majestic-Sapphire CNBC

Mammoth-St. Anthony USAZ

Marietta USMT

Mineral Park USAZ

Minniehaha CNBC

Molly Gibson CNBC

Monitor CNBC

Montezuma CNBC

Mountain Chief and vicinity CNBC

Mountain Con CNBC

Noonday CNBC

North Cerbat (Golconda) USAZ

Northern Bell-Jackson CNBC

Payne Group CNBC

Pennsylvania USCO

Queen Bess and vicinity CNBC

Rambler-Cariboo CNBC

Rio CNBC

Robert Emmet USMT

Santiago-Commonwealth-Centennial USCO

Scraton-Pontiac-Sunset CNBC

Silversmith-Richmond-Ruth-Hope CNBC

Slocan-Sovereign CNBC

Soho CNBC

Standard and vicinity CNBC

Stockton USAZ

Sunshine-Corinth CNBC

Surprise-Noble Five and vicinity CNBC

Treasure Hill USAZ

Tybo USNV

Union USNV

Utica CNBC

Vancouver Group CNBC

Von Roi-Hewitt-A.U. CNBC

Wellington CNBC

Wintrop CNBC

Wonderful-Elkhorn CNBC