U.S. Geological Survey home page

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
For more information on the library, see: local link web link

TITLE: Alunite_NH4+Jarosite NMNH145596A DESCRIPT

DOCUMENTATION_FORMAT: MIXTURE

SAMPLE_ID: NMNH145596

MIXTURE_TYPE: Intimate

MIXTURE: Ammonioalunite + Jarosite

FORMULA: NH4Al3(SO4)2(OH)6 and KF3+3(SO4)2(OH)6

FORMULA_HTML: NH4Al3(SO4)2(OH)6 and KFe3+3(SO4)2(OH)

COLLECTION_LOCALITY: Geyers, California

ORIGINAL_DONOR: National Museum of Natural History

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

The sample was a physical mixture of ammonioalunite, ammoniojarosite and amorphous silica.

IMAGE_OF_SAMPLE:
Photo of sample

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV
File: amalnite.out, -.mdi
References: JCPDS #42-1334, 26-1014
Found: Ammonioalunite > ammoniojarosite; strong unidentified reflection at 2.34 angstroms

Comment: Optically (in oil of refractive index 1.58) both the bulk sample and the sample used for the X-ray pattern appear to be composed on one phase of refractive index approximately 1.58. The c cell dimension of the jarosite is greater than that of Na-jarosite (compare GDS100, GDS101) and K-jarosite (compare GDS99), thus this jarosite is designated ammoniojarosite

J.S. Huebner, J. Pickrell, T. Schaefer, written communication (USGS)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Grains for the current spectrum were hand-picked. Weak absorptions due to jarosite at 0.437, 0.6, 0.9, and 2.26 µm indicate some remaining contamination, but the spectrum shows beautiful ammonium bands in the 2-2.2 µm region. G. Swayze.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns