Unnamed Corundum occurrences , Soboba Hot Springs (Ritchey Hot Springs; White Sulphur Spring), San Jacinto Mts, Riverside Co., California, USA
|Latitude & Longitude (WGS84):||33° 51' 9'' North , 116° 54' 4'' West|
|Latitude & Longitude (decimal):||33.85270,-116.90120|
|Köppen climate type:||Csa : Hot-summer Mediterranean climate|
Corundum occurrences located in Sec. 5, T4S, R1E, SBM, about 6.4 km (4.0 miles) NNE of Soboba Hot Springs (based on the coordinates of record for sec. 5), near the summit of the mountains. Is this locality the same as the Hazen Corundum prospect?
The deposits are located along the contact of granodiorite/quartz diorite host rock and metamorphosed marine sediments. Several small biotite schist bodies at the contact zone contain random sprays and clusters of corundum crystals, up to 2 feet long and 3 inches in diameter. The crystals are included with biotite so severely that in some crystals there is partial replacement. Much of the schist has been decomposed to an iron-stained micaceous clay, which contains inclusions of quartz and feldspar. Quartz veins with feldspar and garnet occur nearby.
According Fred Rynerson, the first report of corundum crystals from the area was made around 1924, by an unnamed woman about 60 years old that had brought a dozen crystals to Ward's Lapidary shop in San Diego for appraisal. The largest crystal was said to have measured approximately 2 inches long, and 3/4 inch at the base, tapering to 1/2 inch at the top. The woman reported that the crystals were scattered over the side of a small hill behind her house. Four years later, Rynerson searched several collections in Riverside County for the source of these crystals, but was unable to find any information about the deposit.
In 1939, large crystals of corundum embedded in mica schist were submitted to the Department of Geology at UCLA, by Mr. B. G. Funk of Los Angeles. These specimens showed sapphire-blue cores, with a progressively zoned gray colored outer rim included with micaceous material. The area was visited around 1940 by Joseph Murdoch and Robert W. Webb, who reported corundum crystals having been found as float in many parts of the San Jacinto Mountains. Several decades later, Mark Rogers reported that several crystals up to 12 inches long, both loose and in schist matrix, had been collected from the area in the late 1940's by a married couple of Asian decent.
In 1980, brothers Ken and Dana Gochenour visited the area several times and eventually discovered a small outcrop of corundum-bearing schist that contained crystals up to 4 inches in length. In 1999, the Gochenours reported finding the remains of an old working that contained a dark biotite schist with broken crystals up to 12 inches long and an inch in diameter. This schist had some crystals that were up to 7 inches long in situ. Several other locations were later discovered while prospecting along the surface, and over 150 pounds of large corundum crystal segments were said to have been collected from the area.
Mindat ArticlesCorundum Crystals from the San Jacinto Mountains by K. L. Gochenour 2000 by Scott L. Ritchie
8 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Late Cretaceous - Middle Jurassic|
66 - 174.1 Ma
|Mesozoic granitic rocks, unit 2 (Peninsular Ranges)|
Age: Mesozoic (66 - 174.1 Ma)
Stratigraphic Name: Bonsall Tonalite; Bradley Granodiorite; Cactus Quartz Monzonite; Cajalco Quartz Monzonite; Corona Hornblende Granodiorite Porphyry; Domenigoni Valley Granodiorite; Escondido Creek Leucogranodiorite; Estelle Tonalite; Fargo Canyon Diorite; Green Valley Tonalite; Home Gardens Quartz Monzonite Porphyry; Indian Mountain Leucogranodiorite; Lakeview Mountain Tonalite; Lake Wolford Leucogranodiorite; La Sierra Tonalite; Mount Hole Granodiorite; Rattlesnake Granite; Roblar Leucogranite; San Jacinto Granodiorite; Stonewall Quartz Diorite; Woodson Mountain Granodiorite
Comments: Peninsular Ranges. Primarily tonalite, granodiorite, and minor quartz monzonite and granite. Emplacement ages mostly 80 to 105 Ma in eastern part of area and 105 to 140 Ma in western part; minor Jurassic rocks in central part
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
66 - 145 Ma
|Mesozoic intrusive rocks|
Age: Cretaceous (66 - 145 Ma)
Lithology: Intrusive igneous rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529.