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Unnamed Quartz-Ti occurrence [1], Big X Mountain, Claussenius, El Dorado Co., California, USAi
Regional Level Types
Unnamed Quartz-Ti occurrence [1]Occurrence
Big X MountainMountain
Claussenius- not defined -
El Dorado Co.County

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Lock Map
Latitude & Longitude (WGS84):
38° 50' 5'' North , 120° 38' 23'' West
Latitude & Longitude (decimal):
Locality type:
Nearest Settlements:
Pollock Pines6,871 (2017)9.4km
Camino1,750 (2011)11.2km
Placerville10,650 (2017)18.1km
Georgetown2,367 (2011)19.0km
Diamond Springs11,037 (2011)21.8km

A decomposing granitic body with quartz intrusions located 2.1 km (1.3 miles) N of Big X Mountain (coordinates of record), 2.1 km (1.3 miles) WNW of the former camp of Claussenius and 8.0 km (5.0 miles) SSE of Quintette.

Large quartz crystals var. smoky and rutile crystals var. sagenite occur in a large area east of Sand mountain road along the Slab Creek drainage. Most of the rutile is found as inclusions in quartz (rutilated quartz). The best site in this area that I know of is on Big X mountain, where Sand Mountain Road crosses Slab Creek. The rutile there is fine hair to pencil lead size crystals, their color is mostly black but some very nice red crystals have been found. The quartz is usually gem quality smoky. There are a limited number of accessory minerals in the deposits, most found as inclusions in quartz crystals; these include chlorite, adularia, anatase, and pyrite (limonite pseudomorph after). The formation consists of quartz veins intruded into a granitic rock. The quartz has a lot of crystallized vugs scattered through it. The granite is mostly decomposed. About 10% of the quartz crystals from this area show some rutilation, 2% are heavily rutilated. There has been no commercial mining of this formation although there are several historic gold mine sites in the area.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

6 valid minerals.

Detailed Mineral List:

Formula: TiO2
Reference: Tony Charlton;
'Chlorite Group'
Reference: Tony Charlton
Formula: Mg5Al(AlSi3O10)(OH)8
Reference: Tony Charlton
Formula: Fe2O3
Reference: Tony Charlton
'K Feldspar'
Reference: Tony Charlton
'K Feldspar var: Adularia'
Formula: KAlSi3O8
Reference: Tony Charlton
Formula: (Fe,O,OH,H2O)
Reference: Tony Charlton
Formula: FeS2
Reference: Tony Charlton
Formula: SiO2
Reference: Tony Charlton
Quartz var: Rutilated Quartz
Formula: SiO2
Reference: Tony Charlton, pers. comm. 2011
Quartz var: Smoky Quartz
Formula: SiO2
Reference: Tony Charlton, pers. comm. 2011
Formula: TiO2
Reference: Tony Charlton

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Group 4 - Oxides and Hydroxides
var: Rutilated Quartz4.DA.05SiO2
var: Smoky Quartz4.DA.05SiO2
Group 9 - Silicates
Unclassified Minerals, Rocks, etc.
'Chlorite Group'-
'K Feldspar'-
'var: Adularia'-KAlSi3O8

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmBnXp, with (m+n):p = 1:2
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings interlayered 1:1, 2:1, and octahedra
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Unclassified Minerals, Mixtures, etc.
'Chlorite Group'-
'K Feldspar'-
'var: Adularia'-KAlSi3O8
var: Rutilated Quartz
var: Smoky Quartz-SiO2

List of minerals for each chemical element

H ClinochloreMg5Al(AlSi3O10)(OH)8
H Limonite(Fe,O,OH,H2O)
O AnataseTiO2
O HematiteFe2O3
O QuartzSiO2
O K Feldspar (var: Adularia)KAlSi3O8
O RutileTiO2
O ClinochloreMg5Al(AlSi3O10)(OH)8
O Limonite(Fe,O,OH,H2O)
O Quartz (var: Smoky Quartz)SiO2
O Quartz (var: Rutilated Quartz)SiO2
Mg ClinochloreMg5Al(AlSi3O10)(OH)8
Al K Feldspar (var: Adularia)KAlSi3O8
Al ClinochloreMg5Al(AlSi3O10)(OH)8
Si QuartzSiO2
Si K Feldspar (var: Adularia)KAlSi3O8
Si ClinochloreMg5Al(AlSi3O10)(OH)8
Si Quartz (var: Smoky Quartz)SiO2
Si Quartz (var: Rutilated Quartz)SiO2
S PyriteFeS2
K K Feldspar (var: Adularia)KAlSi3O8
Ti AnataseTiO2
Ti RutileTiO2
Fe HematiteFe2O3
Fe PyriteFeS2
Fe Limonite(Fe,O,OH,H2O)

Regional Geology

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

Triassic - Ordovician
201.3 - 485.4 Ma

ID: 2902487
Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada)

Age: Phanerozoic (201.3 - 485.4 Ma)

Stratigraphic Name: Calaveras Complex; Shoo Fly Complex; Blue Canyon Formation; Briceburg Formation; Cape Horn Slate; Delhi Formation; Hite Cove Formation; Kanaka Formation; Relief Quartzite; Tightner Formation

Description: Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite

Comments: Western Sierra Nevada. Lower Paleozoic Shoo Fly Complex and upper Paleozoic to lower Mesozoic Calaveras Complex, undivided. Deformed and metamorphosed rocks composed primarily of quartzite, argillite, and chert; includes melange Original map source: Saucedo, G.J., Bedford, D.R., Raines, G.L., Miller, R.J., and Wentworth, C.M., 2000, GIS Data for the Geologic Map of California, California Department of Conservation, Division of Mines and Geology, CD-ROM 2000-07, scale 1:750,000.

Lithology: Major:{argillite,quartzite,phyllite}, Minor:{mudstone,sandstone,chert}, Incidental:{schist, marble, conglomerate, sedimentary breccia, limestone, basalt}

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. [133]

Devonian - Silurian
358.9 - 443.8 Ma

ID: 3185269
Paleozoic sedimentary and volcanic rocks

Age: Paleozoic (358.9 - 443.8 Ma)

Comments: Mccloud Arc

Lithology: Mudstone-carbonate-sandstone-conglomerate

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. [154]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License


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Charlton, Tony (2011) personal communication to

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