DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS84

MINERAL_TYPE: Sulfate

MINERAL: Alunite (Na03) (Alunite group)

FORMULA: KAl3(SO4)2(OH)6 Na03

FORMULA_HTML: KAl₃(SO₄)₂(OH)₆(Na₀₃)

COLLECTION_LOCALITY: Marysvale, UT

ORIGINAL_DONOR: Roger Stoffregen, SMU

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This alunite sample is from a high temperature, coarse vein deposit.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: kalnt84.out, *.mdi (smear mount on quartz plate)
References: JCPDS #14-136; GDS-97B
Found: Alunite

Comment: Moderately sharp reflections; the (003)-(101) doublet is poorly resolved, in contrast to GDS-97B. There may be compositional heterogeneity. Weak to very weak reflections do not appear on the JCPDS card; they could be alunite reflections, or they could be caused by trace quantities of impurities. Lattice spacings are smaller than those that JCPDS #14-136 report for an alunite from the same locality, Marysvale, Utah.

J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Standard used by Stoffregen et al.

Stoffregen, R., and Alpers, C., 1992, Observations on the unit-cell dimensions, H2O contents and del D values of natural and synthetic alunite: American Mineralogist, v.77, p. 1092-1098.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal Grain size distribution:
mode 1: 400 µm @ 65 vol%
mode 2: 40 µm @ 35 vol%

avg gr sz = 260 µm

Trace of Fe-staining on larger gtrains as discontinuous crust covering or clouding 5-10% of grains. Uniaxial (+), good basal cleavage, all consistent with alunite. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 204 0.2-3.0µm 200 g.s.= 260 µm

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=