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: Jarosite WS368 (Pb) DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS368

MINERAL_TYPE: Sulfate

MINERAL: Pb-bearing jarosite (Alunite group)

FORMULA: Pb(Fe+3)6(SO4)4(OH)12

FORMULA_HTML: PbFe⁺³₆(SO₄)₄(OH)₁₂

COLLECTION_LOCALITY: Tombstone, Arizona

ORIGINAL_DONOR: Wards Science Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV (plumjaro.out), 7.3-9.5 keV (plumjar2.out, pbjaro3.out)

References: JCPDS #18-698, 22-827, and 5-417; Szymanski (1985); pattern for K-jarosite GDS98
Found: an alunite, probably K-jarosite, plus subordinate cerussite and quartz.
Sought but not found: plumbojarosite

Comments: Three phases found. Uncorrected alunite 2 theta values were refined to a hexagonal/rhombohedral unit cell having a=7.301 (2) and c=17.050(7). These dimensions and the yellowish ochre color suggest that the alunite is Fe-rich; the pattern closely matches that of K-jarosite except that the strong (012) reflection is missing. There is no evidence of the double cell (c=33.8 Angstroms) characteristic of plumbojarosite (in which a large divalent cation replaces the alkali).

J.S. Huebner,J. Pickrell, T. Schaefer, unpublished data, written communication, USGS, Reston, VA (1994).

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

Comparison with a spectrum of cerussite indicates that any cerussite is not detected spectrally. Since the spectral features of this sample differ from those of low temperature K-jarosite (GDS98), this may indicate the presence of Pb in the sample. Because this sample also contains some cerussite, any chemical analysis must be done on the jarosite portion only. This has yet to be done. G. Swayze.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

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