Sample Description USGS Spectral Library Version 7

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
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TITLE: Alizarin_crimson (dk) GDS780 DESCRIPT

DOCUMENTATION_FORMAT: Man_Made

SAMPLE_ID: GDS780

MATERIAL_TYPE: Paint Pigment

MATERIAL: Paint Pigment

FORMULA: C14H8O4 or C14H6O2(OH)2

FORMULA_HTML: C₁₄H₈O₄ or C₁₄H₆O₂(OH)₂

COLLECTION_LOCALITY: Phillips Collection, Washington, D.C

ORIGINAL_DONOR: Patricia Favero

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Lab

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Lab

SAMPLE_DESCRIPTION:

Dry powdered paint pigment from Kremer Pigments Inc.

Visual examination in sunlight indicates this sample is bright deep red.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

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:

This pigment has a sigmodialy shaped electronic absorption edge centered at about 0.64 microns where reflectance drops from nearly 30% to 1% in a broad visible absorption centered at 0.524 microns. The upper part of the absorption edge is composed of a broad shallow shoulder centered at 0.714 microns. The NIR has many diagnostic vibrations forming a series of sharp absorptions of variable strength at 1.136, 1.206, 1.441, 1.670, 1.724, 1.761, 1.938, 1.988, 2.147, 2.207, 2.305, 2.346, and 2.42 microns (continuum removed positions). G. Swayze

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns