Mineral Evolution Database

Created and maintained by the Mineral Evolution Project in partnership with RRUFF and mindat.

Mineral locality data provided by mindat.org

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The goal of this page is to present localities at which the mineral is found, and estimates of the oldest possible geologic age of the minerals at these localities.

Locality Name:
Downieville District, Sierra Co., California, USA

Oldest recorded age at locality: 388
Youngest recorded age at locality: 2

mindat Locality ID: 217067
mindat URL: http://www.mindat.org/loc-217067.html

Tectonic Settings:

Total number of sublocalities beneath "Downieville District, Sierra Co., California, USA": 123
Total number of bottom-level sublocalities: 118

Number of Child Localities: 4
Child Localities:
China Flat
Downieville
Fir Cap
Red Ant

Latitude: 39°34'55"N
Longitude: 120°49'13"W
Decimal Degree (lat, lon): 39.581944444444,-120.82027777778

A	This mineral is Anthropogenic.
G	This mineral is directly dated.
B	This mineral is reported as having this age.
Y	This mineral is using an age reported as an element mineralization period.
O	This mineral is using an age calculated from all data at the locality.
R	The age displayed for this mineral originates from a different, non-child locality.
P	The age displayed for this mineral is the range of ages for this mineral at all of this locality's children.
	This mineral's age has not yet been recorded.

Arsenic	Arsenopyrite	Chlorite	Clay	Copper	Garnet	Mica	None	Pyrite	Quartz
Rocksalt	Spinel	Stibnite	Talc

Arsenopyrite ()*	Bismuth ()*	Chromite ()*	Clinochlore ()*	Galena ()*
Gold ()*	Magnesiochromite ()*	Muscovite ()*	Pyrite ()*	Quartz ()*
Silver ()*	Stibnite ()*	Talc ()*	Uvarovite ()*

This Mineral list contains entries from this locality, including sub-localities. Minerals in bold are reported by mindat.org as occurring directly at this locality, and do not occur at any children (sublocalities) of this locality.

Elements at this locality, including sub-localities: Ag Al As Au Bi Ca Cr Fe H K Mg O Pb S Sb Si

Elements from minerals reported directly at this locality:

Structural Groups for minerals in this locality:
Arsenic Arsenopyrite Chlorite Clay Copper Garnet Mica None Pyrite Quartz
Rocksalt Spinel Stibnite Talc

14 IMA Minerals at location:

Mineral name	Structural Groups	IMA Formula	Max Age (Ma)	Min Age (Ma)	# of Sublocalities containing mineral	LOCALITY IDs, not mindat ids	# of localities containing mineral
Arsenopyrite ()*	Arsenopyrite	FeAsS			3	177494,177519,177571	9052
Bismuth ()*	Arsenic	Bi			1	177521	1966
Chromite ()*	Spinel	Fe²⁺Cr₂O₄	388	388	2	177478,177564	3902
Clinochlore ()*	Chlorite Clay	Mg₅Al(AlSi₃O₁₀)(OH)₈	388	388	1	177512	1756
Galena ()*	Rocksalt	PbS			1	177534	24243
Gold ()*	Copper	Au	388	2	70	177456,177457,177458,177459,177461,177462,177463,177464,177465,177466,177469,177470,177472,177473,177476,177479,177481,177482,177483,177485,177486,177487,177489,177490,177491,177493,177494,177495,177496,177498,177499,177501,177502,177503,177506,177507,177508,177509,177510,177511,177512,177513,177515,177517,177519,177522,177523,177524,177525,177526,177530,177535,177536,177540,177548,177552,177554,177556,177557,177559,177560,177562,177563,177567,177568,177569,177570,177571,177572,177575	30554
Magnesiochromite ()*	Spinel	MgCr₂O₄	388	388	2	177512,177551	311
Muscovite ()*	Mica Clay	KAl₂(Si₃Al)O₁₀(OH)₂			1	177493	17380
Pyrite ()*	Pyrite	FeS₂			2	177489,177502	39462
Quartz ()*	Quartz	SiO₂	388	388	37	177458,177459,177461,177462,177464,177465,177466,177470,177472,177473,177479,177485,177493,177494,177495,177496,177502,177503,177507,177509,177510,177512,177517,177519,177522,177526,177530,177536,177548,177552,177554,177556,177563,177568,177569,177571,177572	61156
Silver ()*	Copper	Ag			1	177459	5186
Stibnite ()*	Stibnite	Sb₂S₃	388	388	1	177469	3418
Talc ()*	Clay Talc	Mg₃Si₄O₁₀(OH)₂	388	388	2	177512,177571	3337
Uvarovite ()*	Garnet	Ca₃Cr₂(SiO₄)₃	388	388	1	177512	212

Locality Notes from all Ages at Locality:

Age ID	Locality Notes
Michelle_0076	Liparite, very near Tolfa (192390)
Michelle_0077	Quartz latite
Michelle_0078	Quartz latite
Michelle_0079	Liparite
Michelle_0080	Quartz latite
Michelle_0081	Liparite
Michelle_0082	Monzonitic porphyry
Michelle_0083	Liparite quartz latite

11 Ages assigned to this locality:

Excel ID	Max Age (Ma)	Min Age (Ma)	Age as listed in reference	Dating Method	Age Interpret	Sample Source	Sample Num	Dated Mineral	Age applies to these Elements	MinDat Locality ID	Dated Locality (Max Age)	Location as listed in reference	Reference	Reference ID	Age Notes
Michelle_0076	4.3	4.1	4.2±0.1	K-Ar	Age of liparite	feldspar	K13			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Rocca di Tolfa	Fornaseri (1985)	RDSIMF40_73	Age of liparite
Michelle_0077	3.4	2.6	3.0±0.4	K-Ar	Age of quartz latite	biotite	K2			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Sso della Strega	Fornaseri (1985)	RDSIMF40_73	Age of quartz latite
Michelle_0078	3.1	2.7	2.9±0.2	K-Ar	Age of quartz latite	feldspar	K2			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Sso della Strega	Fornaseri (1985)	RDSIMF40_73	Age of quartz latite
Michelle_0079	3.8	3.6	3.7±0.1	K-Ar	Age of liparite	feldspar	K12			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Fso d. Melledra	Fornaseri (1985)	RDSIMF40_73	Age of liparite
Michelle_0080	2.6	2.2	2.4±0.2	K-Ar	Age of quartz latite	feldspar	K5			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	La Tolfaccia	Fornaseri (1985)	RDSIMF40_73	Age of quartz latite
Michelle_0081	2.2	2	2.1±0.1	K-Ar	Age of liparite	feldspar	K3			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	La Montagnola	Fornaseri (1985)	RDSIMF40_73	Age of liparite
Michelle_0082	3.6	3.4	3.5±0.1	K-Ar	Age of monzonitic porphyry	feldspar	K15			93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Pgio della Stella	Fornaseri (1985)	RDSIMF40_73	Age of monzonitic porphyry
Michelle_0083	3.4	3.2	3.3±0.1	K-Ar	Age of Liparite quartz latite	sanidine	K14	Sanidine		93202	Cuba Placer Mine, China Flat, Downieville District, Sierra Co., California, USA	Mt Riccio	Fornaseri (1985)	RDSIMF40_73	Age of liparite quartz latite
podchrome-00189	388	388	pre-Early Devonian-Jurassic (388±17 Ma U-Pb zircon from felsic igneous rocks; 174 Ma K-Ar white mica from blueschists)						Cr	93512	Oxford Mine (Oxford Mine And Mill; Oxford Lease And Mill; Becky; Case And Myers; Mt. Holly; Gold Bluff; Good Hope; Good Hope Extension No. 2; Jefferson No. 2 Claim; Milton Claim), Downieville, Downieville District, Sierra Co., California, USA	Oxford Pit 1	Moiser et al. (2012)	USGSSIR2012_5157
podchrome-00187	388	388	pre-Early Devonian-Jurassic (388±17 Ma U-Pb zircon from felsic igneous rocks; 174 Ma K-Ar white mica from blueschists)						Cr	93431	White Bear Mine (Unnamed Cr-Au Mine [1]), Fir Cap, Downieville District, Sierra Co., California, USA	White Bear	Moiser et al. (2012)	USGSSIR2012_5157
podchrome-00188	388	388	pre-Early Devonian-Jurassic (388±17 Ma U-Pb zircon from felsic igneous rocks; 174 Ma K-Ar white mica from blueschists)						Cr	93266	Fraction Claim (Golconda Mine), Red Ant, Downieville District, Sierra Co., California, USA	Golconda Fraction	Moiser et al. (2012)	USGSSIR2012_5157

Sample	Source Locality	Reference URL

All locality data graciously provided by mindat.org

All age data...