TITLE: Arsenopyrite HS262 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS262

MINERAL_TYPE: Sulfide

MINERAL: Arsenopyrite (Arsenopyrite group)

FORMULA: FeAsS

FORMULA_HTML: FeAsS

COLLECTION_LOCALITY: Gold Hill, Utah

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Spectra for this sample were originally published in: Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: IV. Sulphides and sulphates. Modern Geology, v. 3, p. 1-14.

With the note: "This sample is contaminated with some quartz and a small amount of pyrite and elemental sulphur. Arsenopyrite is opaque and spectrally featureless. Its opacity is caused by the conduction band extending over the entire range, mainly due to the presence of arsenic. The contaminants in this sample are not abundant enough to alter this behaviour, and the fact that the largest paritcle size falls approximately in the middle of its reflectivity range has no real significance."

Sample measured for the library was the 74-250µm sieve interval.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV
File: arsn263.mdi, *.out (smear mount on quartz plate)
References: JCPDS #42-1320; Huebner's reference patterns
Found: Quartz, arsenopyrite, unindexed weak to very weak reflections at 6.3, 4.5, 3.42, 3.18, 2.86, and 2.75 angstroms

Comment: Quartz reflections of moderate intensity (the (100) peak of nominal relative intensity 22% did not exceed 200 counts.sec-1), arsenopyrite reflections much weaker. Unindexed reflections could not be identified, suggesting they may represent more than one phase. Peaks are symmetric and of normal width, but alpha1-alpha2 wavelength resolution is poor. Phases are only moderately crystalline.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

av gr sz = 265µm for arsenopyrite

59 vol% quartz
40 vol% arsenopyrite
1 vol% elemental sulfur

Optically opaque, grayish yellow metallic luster. Suggest magnetic separation be done on this sample. 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 583 0.2-3.0µm 200 g.s.= 265µm

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

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