Sample BHS

NavDat sample number 3667 · GRANITE

Sample

Sample ID	BHS
Rock name	GRANITE
Rock type	PLUTONIC
Composition	FELSIC
Material	IGNEOUS
Comment	medium to coarse grained, light-gray, uniformly textured; white, subhedral K-feldspar phenocrysts as much as 10 cm in size are present and contain rare dark specks zonally arranged; groundmass consists of white plagioclase, biotite, quartz, and conspicuous, honey-yellow sphene; faint primary foliation caused by alignment of biotite

Location

Latitude	45.5872
Longitude	-112.949
Location	outcrop just E of summit of Barbour Hill; Beaverhead County
State / province	Montana
Volcanic field	Pioneer Batholith

Age

Age (Ma)	Error	Min	Max	Geologic age	Dated by
72.3		69.8	74.8

Analyses

Whole rock

Item	Value	Std. dev.	Unit	Method
SIO2	72.8		WT%	RAPID_ROCK
AL2O3	15.1		WT%	RAPID_ROCK
FE2O3	0.86		WT%	RAPID_ROCK
FEO	0.76		WT%	RAPID_ROCK
MGO	0.43		WT%	RAPID_ROCK
CAO	2.2		WT%	RAPID_ROCK
NA2O	3.1		WT%	RAPID_ROCK
K2O	3.5		WT%	RAPID_ROCK
H2O_PLUS	0.96		WT%	RAPID_ROCK
H2O_MINUS	0.14		WT%	RAPID_ROCK
TIO2	0.2		WT%	RAPID_ROCK
P2O5	0.18		WT%	RAPID_ROCK
MNO	0.08		WT%	RAPID_ROCK
CO2	0.02		WT%	RAPID_ROCK
TOTAL	100		WT%	RAPID_ROCK

References

Zen, E-an; Marvin, R F; Mehnert, H H (1975) Preliminary petrographic, chemical, and age data on some intrusive andassociated contact metamorphic rocks, Pioneer Mountains, southwesternMontana. Geological Society of America Bulletin, vol.86, no.3, pp.367-370,1975 doi:10.1130/0016-7606(1975)86<367:PPCAAD>2.0.CO;2