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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS784
MATERIAL_TYPE: Paint Pigment
MATERIAL: Paint Pigment
FORMULA:apparently prepared from the roots of the madder plant's roots with an alum substrate.
FORMULA_HTML: apparently prepared from the roots of the madder plant's roots with an alum substrate.
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 dark 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 strong absorption edge centered at about 0.70 microns where reflectance drops from nearly 80% to 2% in a broad visible absorption centered at 0.502 microns with a shoulder at 0.557 microns. The NIR has many diagnostic vibrations forming a series of sharp absorptions of variable strength. There is a complex of absorptions centered at 1.50 microns with individual absorptions at 1.397, 1.417, 1.451, 1.516, 1.550, and 1.585 microns. Another absorption complex centered near 2.27 microns consists of individual absorptions at 2.206, 2.267, 2.318, and 2.362 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