Mineral Evolution Database
Created and maintained by the Mineral Evolution Project in partnership with RRUFF and mindat.
Mineral locality data provided by mindat.org

Ages for Muscovite at Helen Beryl Mine (Sweepstakes Beryl; Big Tom Claim; Kem Claim), Fourmile, Custer District, Custer Co., South Dakota, USA

The cyan highlights indicate which age entries were selected as the "best" for assigning the mineral an age of 1702Ma - 1702Ma at this locality

Locality age (remote)

Excel ID	Max Age (Ma)	Min Age (Ma)	Dated Mineral	Minerals explicitely stated as having this age	Age applies to these Elements	Dated Locality ID	Dated Locality	Ref	Ref ID
Be-00023	1702	1702		Ehrleite, Fransoletite, Greifensteinite, Pahasapaite, Parafransoletite, Roscherite, Tiptopite	Be	4122	Tip Top Mine (Tip Top Pegmatite), Fourmile, Custer District, Custer Co., South Dakota, USA	Dahl and Foland (2008)	AM93_1215
Be-00046	1702	1702		Faheyite	Be	45259	Roosevelt Group (Rough Rider), Custer, Custer District, Custer Co., South Dakota, USA	Dahl and Foland (2008)	AM93_1215