Mineral Evolution Database

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

Mineral locality data provided by mindat.org

The Mineral Evolution database is currently under development.

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:
O'Brien Mine (S-Bend Mine), Coloma, Coloma District, West Belt, El Dorado Co., California, USA

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

mindat Locality ID: 77999
mindat URL: http://www.mindat.org/loc-77999.html

Tectonic Settings: Oceanic Arc (Subduction)

Total number of sublocalities beneath "O'Brien Mine (S-Bend Mine), Coloma, Coloma District, West Belt, El Dorado Co., California, USA": 0
Total number of bottom-level sublocalities: 0

Latitude: 38°49'53"N
Longitude: 120°54'3"W
Decimal Degree (lat, lon): 38.831388888889,-120.90083333333

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.

Clay	None	Spinel	Talc

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: Cr Fe H Mg O Si

Elements from minerals reported directly at this locality: Cr Fe H Mg O Si

Structural Groups for minerals in this locality:
Clay None Spinel Talc

2 IMA Minerals at location:

Chromite ()*	Talc ()*

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
Chromite ()*	Spinel	Fe²⁺Cr₂O₄	388	388	0		3902
Talc ()*	Clay Talc	Mg₃Si₄O₁₀(OH)₂	388	388	0		3337

1 Ages assigned to this locality:

	Excel ID	Max Age (Ma)	Min Age (Ma)	Age as listed in reference	Dating Method	Age Interpret	Prioritized?	Sample Source	Sample Num	Run Num	Age from other Locality	Dated Mineral	Minerals explicitely stated as having this age	Age applies to these Elements	MinDat Locality ID	Dated Locality (Max Age)	Location as listed in reference	Reference	Reference DOI	Reference ID	Age Notes
	podchrome-00120	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	77999	O'Brien Mine (S-Bend Mine), Coloma, Coloma District, West Belt, El Dorado Co., California, USA	O'Brien	Moiser et al. (2012)		USGSSIR2012_5157

Sample	Source Locality	Reference URL

All locality data graciously provided by mindat.org

All age data...