Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Ammonio-alunite NMNH145596 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH145596

MINERAL_TYPE: Sulfate

MINERAL: Ammonioalunite

FORMULA: NH4Al3(SO4)2(OH)6

FORMULA_HTML: NH₄Al₃(SO₄)₂(OH)₆

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. Grains for the sample for the current spectrum were hand-picked by G. Swayze. Weak absorptions due to jarosite at 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. There are weak bands due to jarosite at 0.6, 0.9, and 2.26 µm.

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, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

The spectrum shows beautiful ammonium bands in the 2-2.2 µm region. There are weak bands due to jarosite at 0.6, 0.9, and 2.26 µm.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1d2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED:	where	Wave Range	Av_Rs_Pwr	Comment
LIB_SPECTRA:	splib04a r 271	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 829	1.5-25 µm	250	g.s.=

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