Lightner Mine (Eastland Mine), Angels Camp, Angels Camp Mining District, Calaveras County, California, USAi

Regional Level Types
Lightner Mine (Eastland Mine)	Mine
Angels Camp	- not defined -
Angels Camp Mining District	Mining District
Calaveras County	County
California	State
USA	Country

A former lode gold mine located in the NE¼ sec. 33, T3N, R13E, MDM, on the southern edge of the City of Angels Camp, on public land (city of Angels Camp). Discovered before 1850. The claims cover at least 420 feet. Operated during the periods 1857, 1896 to 1910, and 1910-1915. MRDS database stated accuracy for this location is 100 meters.

The Lightner Mine at Angels Camp, between the Utica and Angels Mines covers only 420 ft. on the Mother Lode. It was first opened and equipped with a 10-stamp mill about 1860, but the material milled from an open cut to a depth of 70 ft. did not repay the cost of operation. Production was resumed, at first from surface ore, in 1896. From then until 1910 it was in steady operation and a producer annually; and after an interruption in 1910 due to the caving of the old shaft, was productive until 1915, since which time there has been no underground work.

The Lightner produced between 1896 and 1915 over $2,500,000. Lightner Gold Mining Company was incorporated in 1896 with a capital of $125,000 in $1 shares, of which 62,287 shares were issued. Dividends amounting to $550,000 are reported, and when the property was closed the management claimed the' mine still contained 200,000 tons of ore above the 300 foot level.

Geologically, the deposit is the same as those in the Angels and Utica mines. The main vein was reported 120 ft. wide between the 4th and 6tli levels but split into three strands on the 6th level, 100 ft. north of the shaft. The 'talc' or 'bull-quartz' vein cut across the main vein between the 500 and 600 foot levels. The ore vein is claimed to have been picked up below the 'talc vein' in a crosscut run 150 ft. on the 900 foot level, but its dip had steepened to 80° E. The walls of the vein are hard, but the country considerably broken by movements caused by the removal of large orebodies in this and the adjoining mines, so heavy square-set timbering had to be employed. After the old shaft had caved in 1910 a new one was sunk 255 ft. from it and levels were turned at 100 foot intervals to a depth of 600 feet This shaft was finally sunk to 1,050 feet

The drainage problem would have to be considered carefully in connection with any plan to reopen and deepen this or Angels Mine, due to the great amount of ground opened in past years in the adjoining mines now standing idle.

The Lightner Mine was originally worked prior to 1857. By 1860, the mine was opened by a 70 foot open cut and equipped with a 10-stamp mill, but the venture proved uneconomical. The mine was idle until 1896, when it was reopened by the newly incorporated Lightner Gold Mining Company with a capitalization of $125,000. By 1897, it was only 200 feet deep, but in 1898 it was being actively developed with new machinery and sufficient ore was being produced to run a new 40-stamp mill.

Except for 1910, during which the mine was shut down due to a caving of the shaft, the mine was continuously active until 1915 when it was shut down (Clark and Lydon, 1962). From 1896 until 1915, approximately 500,000 tons of ore were mined which yielded more than $3 million. Ultimately, the Lightner Gold Mining Company paid $550,000 in dividends, and when the property was closed the company claimed the mine still contained 200,000 tons of ore above the 300-foot level (Logan, 1934).

The mine was dewatered in 1920, but there was no production and it has been idle ever since (Clark and Lydon, 1962).

Mineralization is a vein deposit (Mineral occurrence model information: Model code 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27), hosted in Mesozoic amphibole schist, slate and and chloritic and talcose schist. The ore body strikes NW and dips NE and is tabular, pinch & swell in form. The vein zone is up to 120 feet wide. The dip is steep to verticle. Above the 600 foot level ore is mineralized schist and slate with quartz and talc. Below this level there are 3 distinct vein zones. A vein of talc xrosses the main vein between the 500 and 600 foot levels. The main vein was reported to be 120 feet wide between the 4th & 6th. levels of workings, but split into 3 strands on the 6th level, 100 feet N of the shaft. Controls for ore emplacement include ore shoots within mesothermal gold bearing quartz veins. There was hydrothermal alteration of wall rock. Ore materials: Quartz-calcite stringer veins containing free gold and auriferous pyrite, and mineralized schist wallrock. Gangue Materials: Quartz, calcite, talc, chalcopyrite, ankerite, and sericite. Local alteration includes ankeritic and sericitic alteration of wall rock with disseminated aurtiferous pyrite mineralization.

Specific information regarding the nature of the ore in the Lightner Mine is meager. However, several records cite its similarity to ore in the adjoining Utica Mine for which there is considerably more information, and from which this description is largely drawn. The stringers range from a few inches to three feet thick and are largely quartz, but carbonate is abundant, especially in the smaller fissures. The stringers strike about N 50? W and dip steeply northeast to vertical, lying nearly in the planes of schistosity of the country rock (Eisenhauer, 1932). Both the quartz and nearby country rock contain free gold and auriferous pyrite. The schist is greatly altered and pyritized and carries the greater gold values. The schists are largely altered and compose of ankerite and sericite, with subordinate quartz, albite, and pyrite.
The richest ore was called "brown quartz", consisting of a fine granular aggregate of quartz, dolomite, and sometimes albite, with abundant small crystals of pyrite. The brown quartz does not always form well-defined veins or stringers, but is intimately associated with the country rock, and is in part an altered form of the country rock. The other vein minerals are free gold, sericite, and chalcopyrite. Gold is not visible in most of the ore, but occurs in considerable masses in certain rich streaks (Ransome, 1900).
The rich brown quartz ore was confined to the shallow workings above the 600-foot level and where the ore body was 120 feet wide. Between the 500 and 600-foot levels the ore body was cut off by a zone of talc 15 to 20 feet thick with a dip of 30? NE (Tucker, 1916). This truncation and a similar talc zone were encountered within the Utica vein in the adjoining Utica Mine where Eisenhauer (1932) and McCurdy (1932) interpreted the abrupt flooring of the ore body to a reverse fault plane within the talc zone, above which the best ore occurred in the hanging wall. The ore body is said to have been picked up below the talc zone in a crosscut run 150 feet on the 900-foot level, but its dip had steepened to between 80?E and vertical (from 65?-71? above the talc) and the ore body had split into three distinctive vein zones, separated by barren schist about 100 feet north of the shaft (Clark and Lydon, 1962).
The grade of ore varied greatly. Information about the ore body in the Utica Mine indicates the shallowest ores yielded as much as $13.02 per ton but declined to $3.60 or less with depth. Occasionally small high-grade pockets were found. Pyrite and chalcopyrite are the only sulfides reported in the ore. Ore averaged about 2% concentrates.

Local rocks include undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided).

Regional geologic structures include the Bear Mountains fault zone and the Melones fault zone.

Workings include underground openings. The Lightner Mine was developed by a 1,050 foot, 3-compartment, vertical shaft. Levels were turned at 200, 300, 400, 500, 600, and 900 feet with drifts on all levels to the claim lines except on the 900 foot level which was driven only 40 feet to the south, for a total of 2150 feet of drifts. From the 600-foot level a winze was sunk to the 900-foot level and a crosscut run to cut the ore body below the talc zone. There was also a cross-cut 150 feet from the shaft on the 900-foot level (Logan, 1934). The mine was substantially timbered with a modification of the square-set system.

Ore was hoisted in 3-ton skips by a double-drum electric hoist and dumped over a grizzly before crushing in a 10 inch x 20 inch Blake crusher. There was a 500-ton storage bin under the crusher.

The mine had a 40-stamp electric mill. Storms (1900) provides a good description of the milling operations at the turn of the century. The mill was later upgraded to 60 stamps. Battery pulp was concentrated on thirty-six 4-foot Frue vanners (Tucker, 1916; Clark and Lydon, 1962). One-half of the gold values were recovered by amalgamation inside the batteries, one-fourth on outside plates, and one-fourth by concentration. Recovery was 90% (Tucker, 1916).

The Lightner Mine reportedly produced in excess of $3 million (Clark, 1970).

Large tonnages of low-grade ore were left. When the mine closed there were supposedly 200,000 tons of ore left above the 300 foot level.

Other Regions, Features and Areas containing this locality

References