Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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TITLE: White_Crust LV30 starkeyite DESCRIPT

DOCUMENTATION_FORMAT: MIXTURE

SAMPLE_ID: LV30

MIXTURE_TYPE: Intimate

MIXTURE: Starkeyite + possible other salts

FORMULA: MgSO4.4H2O

FORMULA_HTML: MgSO₄.4H₂O

COLLECTION_LOCALITY: Arkansaa river Site 3 km south of Leadville, Colorado, USA

ORIGINAL_DONOR: Gregg Swayze

COLLECTION_LATITUDE: Not Available # degrees and decimal minutes (N or S)

COLLECTION_LONGITUDE: Not Available # degrees and decimal minutes (W or E)

DATUM: Not Available # coordinate datum

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory, Denver, Colorado

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory, Denver, Colorado

SAMPLE_DESCRIPTION:

White Crust, starkeyite, Arkansas River Site Leadville LV30. This crust formed about saturated fluvial mine tailings rich in pyrite. Apparently water saturated with salts wicked up through permeable fine-grained sand and formed the white salt crust at the surface when the liquid evaporated. It may be possible that the epsomite is mixed with other salts and trace metals may substitute for Mg (e.g. As etc). This type of salt deposit is typical of acid mine drainage and when dissolved by rain or other precipitation causes a quick release of metals into streams.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Starkeyite(Major), Quartz(Major), Albite (trace), Muscovite (trace). Sutley, 2005. The presence of quartz, albite, and muscovite in addition to starkeyite is due to mixing of the white starkeyite coating with underlying fluvial sediments. The spectrum represents the starkeyite only.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: NONE # XRF, EPMA, ICP(Trace),WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

none

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

none

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

The spectral features closely resemble those of epsomite in standard GDS149. The presence of a band at 1.6237 and 2.207 may be diagnostic of starkeyite and perhaps other salts. The XRD analysis includes material from the underlying sediments but the spectrum is of the white crust only.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns