Report of the State Mineralogist . e andGottfried Company. Point Molate Quarry. The quarry is at the edge of San FranciscoBay 2 miles north of Point Eichmond. The rock is a hard gray meta-morphosed sandstone of the Franciscan formation. It is quarried in alarge open cut whose face varies up to 100 ft. in height. Two steamshovels are in operation on the main floor of the crushing plant. Ina pit 10 ft. below the main floor, 4 bull-wheel derricks are used to loadrock in portable bunkers. These bunkers feed to skips which transport CONTRA COSTA COUNTY. 63 the rock to the crushing plant. This plant
Report of the State Mineralogist . e andGottfried Company. Point Molate Quarry. The quarry is at the edge of San FranciscoBay 2 miles north of Point Eichmond. The rock is a hard gray meta-morphosed sandstone of the Franciscan formation. It is quarried in alarge open cut whose face varies up to 100 ft. in height. Two steamshovels are in operation on the main floor of the crushing plant. Ina pit 10 ft. below the main floor, 4 bull-wheel derricks are used to loadrock in portable bunkers. These bunkers feed to skips which transport CONTRA COSTA COUNTY. 63 the rock to the crushing plant. This plant is equipped with two No. 5and two No. 3 gyratory crushers, trommels, bucket elevators and beltconveyors. It is operated by electric power. Steam power generatedwith crude oil fuel is used for operating derricks and hoists. Forty menare employed. The rock is used mostly for concrete in San FranciscojUid vicinity, to which it is shipped in barges at the quarry. Owner,Healy-Tibbets Construction Company, 9 Main street, San Photo No. 7. Point Molate Quarry looking westward, showing method of handling rockfrom pit by bull-wheel derricks. Point Richmond Quarry. The Hutchinson Company, 444 Seven-teenth street, Oakland, have been operating this quarry for the past fiveyears. The rock is metamorphosed sandstone closely resembling thatof the Point Molate and San Pablo quarries. It is quarried in a largecircular open cut whose face is about 85 feet high. Air drills are stone is shoveled into lj-yard cars and hauled by cable up anincline to the crushing plant. This consists of one No. 4 and one No. 3gyratory crushers, bucket elevators and trommels having a capacity of300 yds. per 10 hours. Electric power is bought of the Pacific Gas andElectric Company. The product can be shipped either by rail or water,as a spur track of the Santa Fe runs within 100 yds. of the plant. Thebest rock is used for concrete, and the poorer quality for ballast. is superintendent.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectminesandmineralresou
