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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: Cuprite HS127 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS127

MINERAL_TYPE: Oxide

MINERAL: Cuprite

FORMULA: Cu2O

FORMULA_HTML: Cu2O

COLLECTION_LOCALITY: Butte, Montana

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This is a relatively pure cuprite sample (analysis indicate 0.008% by weight Fe). Transition of the cupric ion in the cuprite crystal field results in absorption feature at 0.85µm.

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: III. Oxides and hydroxides. Mod. Geol., 2, pp. 195-205. END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: cupr127_mdi (smear mount on quartz plate)
References: JCPDS #41-254, 41-1390; Huebner's reference patterns
Found: cuprite, malachite, minor quartz, unindexed reflection at 3.23 angstroms

Comment: Cuprite and quartz reflections sharp, indicating good crystallinity. Many malachite reflections could be indexed and compare well with a weak reference pattern of malachite from the SSH collection.

J.S.Huebner, J.Pickrell, T. Schaefer, written communication(1994 USGS)

Also::::

40 kV - 30 mA, 6.5-9.5 keV
File: cupr127.out, *.mdi; cupr127b.out, *.mdi
References: JCPDS #41-254, 41-1390, 4-836, and Huebner's reference patterns
Found: Cuprite >> quartz > malachite, copper (?), unidentified weak reflection at 3.23 angstroms
Sought but not found: chalcocite, covellite, digenite, chalcopyrite, pyrite, goethite, hematite, magnetite, brochantite, atacamite, antlerite, azurite

Comment: Strong and sharp cuprite pattern - the material is well crystallized. All other reflections of moderate to very weak intensity. The quartz identification is based on the (100) and (101) reflections only. Malachite is based on five very weak reflections. The copper is based on a weak (111) and very weak (220). [The copper (111) could be pyrrhotite (10-12), but that would leave unexplained the reflection at the position of the copper (220).]

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:
77 vol% cuprite
10 vol% quartz
10 vol% azurite-malachite
3 vol% white soft mineral

Red metallic luster is diagnostic of cuprite. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_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 1323 0.2-3.0µm 200 g.s.= 269 µm
LIB_SPECTRA: splib05a r 2296 0.2-3.0µm 200 g.s.=


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