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The East Beaver District is an explored area of two and one-half by one and one-half miles in the southeastern corner of Teller county, where the development of important copper ore bodies seems likely.
Its nearness to the Cripple Creek gold district, which is about seven miles to the west, appears to have been a drawback to exploitation commensurate with its surface copper indications. It is most readily accessible by a seven mile wagon road from Rosemont station on the Colorado Springs and Cripple Creek District railway.
East Beaver creek and its branches traverse the region. The elevation is about 9,000 feet. The rugged slopes of the mountains are timbered in places. Coarse-grained granites and gneisses with occasional intrusive dikes of diorite and diabase are the geological characteristics. Fissure veins cut the granite and gneisses, usually in proximity to, but sometimes removed from, the eruptive masses.
Gossan, sometimes green-stained with malachite, are often conspicuous outcropping cappings of the veins which are of a width of from two feet to twelve feet. The important ores are sulphides encountered at depths of from 50 feet to 150 feet. The associated gold values are appreciable.
The Big Four property was worked for its copper ore in 1894, at which time a small concentrating plant was erected but never operated. Several shipments of ten per cent and twelve per cent copper ore were made, but operations were suspended on account of misdirected development.
In 1901, it was relocated as the Colorado. A vein of an average width of four and one-half feet has been shaft-opened to a depth of 150 feet, and at the 70 foot and 125 foot points there are drifts in ore.
The ore is massive pyrites and chalcopyrites in hard quartz. On the dump there is a considerable tonnage of ore, the bulk of which might profitably be concentrated and some of which could be sorted to a ten per cent or twelve per cent, shipping product.
The gold and silver contents run from 40 cents to $4. Selected dump ores gave assay returns of 30.9 per cent copper, 1 ounce silver and 0.02 ounces gold, and grab samples of the entire dump showed six and one-half per cent, and nine and one-half per cent, copper with small gold and silver values.
There is a machinery plant at the shaft. The property has been idle for some time on account of disagreements among the stockholders of the company.
The June property to the east is developed by a 103 foot shaft which discloses a three foot vein. A ten and one-half ton shipment, made in 1905, gave net returns of $23.40 to the ton.
To develop this lode to a depth of 800 feet a 1,000 foot tunnel is in progress; it has been driven 600 feet and a three foot vein of two per cent to three per cent copper values has been intersected.
The Beaver Valley Gold Mining Company is shaft-exploiting a five foot vein at a point 5,000 feet to the north of the Colorado. At a depth of 163 feet water has begun to seriously interfere with sinking operations.
Considerable quantities of ore assaying fifteen per cent and eighteen per cent copper are reported to have been broken. There is a hoisting equipment for the prosecution of sinking to the 500 foot depth.
The Golden Belle, Homestake, Nebraska, Copper Age, Specimen, Ajax and several other locations are shallow-prospected by shafts and tunnels, and sulphide ores of small percentage in copper have been disclosed.
The increase in copper contents, as well as the greater width of the ore bodies, as depth is attained, is an encouraging feature of the development.