Show QUARTZ MINING IN SIERRA COUNTY WRITTEN FOR THE MINING REVIEW BY G CHESTER BROWN E M I 1 san francisco april 24 the rich chutes of ore found in sierra county during the past two years has caused a revival of interest in all the mining properties in this county and much activity is shown in the vicinity of the town of forest the forest district has been a big producer of high grade ore and many of the old prospects are now being worked this region is forty five miles northeast of nevada city the supply point and as the road is only open for heavy hauling for eight months of the year all winter supplies must be delivered during this time the middle fork of the yuba river oregon creek and many other smaller streams stream s traverse this section plenty of wood and water for all ail mining purposes is at hand U POKII 0 epif 9 art F wo the formation consists of a contact between the serpentine and the slate with an intrusion of porphyry this porphyry seems to have an influence on the deposition of the ore bodies as the veins lie along side this porphyry the ore deposition seems to be along three belts of serpentine for a width of five miles the ore occurring near the igneous intrusions the slates lie between these serpentine belts and the surface is covered with a capping of lava subsequent to the formation of the ore bodies faulting and broken ground is to be found until the zone of disturbance is passed through but with depth permanent leads are found and mines with large tonnage opened up the vein matter consists of a hard quartz with a gouge of high grade on each wall varying in width from three to twelve inches the vein proper has a width of eight to ten feet with values from 4 to 6 per ton in gold the and pyrite are often very rich but the rich pockets occur in the oxidized portion of the vein matter the slate and the porphyry also contain values in places crop pings can be seen that contain about 4 per ton in gold but as a rule the surface is covered with undergrowth and a capping of lava the dip of the vein is about 60 degrees to the east with well defined walls surface prospecting is done by means of open cuts at points where the cropping is exposed As the country is mountainous all the work is done by means of tunnels and considerable backs are obtained the cost of mining is not excessive for in some mines tunnels have been run for 4 per foot the ground is firm and does not require much timbering and it breaks well hand drilling is used in many of the properties the high grade ore is sorted and shipped to a smelter while the average grade is milled with a large milling plant the cost of mining arid and milling t does not exceed 2 per ton cyanide plants are very successful as the tailings are easily worked the milling process consists of the use of heavy stamps amalgamation fine grinding after amal gation and direct of the total product from the stamps without intermediate concentration the production of this section cannot be accurately determined due to the number of small prospects producing high grade ore but the following properties have produced over a million in gold the kate hardy is a rich mine with a production of over one million and has a milling vein of a width of ten feet it is worked by means of tunnels and large droppings crop pings are exposed it is located on oregon creek and three miles west of the town of forest the old brush creek mine north of the kate hardy has a foot shaft and produced about one million from milling operations from this shaft the omega above the kate hardy is also a good producer and has a strong lead the most noted mine on this same lead is the fightner Tight ner at alleghany allegheny Alleg hany this property is on the middle belt of the serpentine and the ore body has been proven to a depth of feet the width of the vein is eight feet and much of the same is shipping ore with only a small force of men this mine is producing per month from a shipment of 1200 pounds over was obtained from the smelter this mine has done much to interest mining men in sierra county G CHESTER BROWN M E |