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: Chrysocolla HS297 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS297.1B, HS297.2B, HS297.3B, HS297.4B

MINERAL_TYPE: Phyllosilicate

MINERAL: Chrysocolla

FORMULA: (Cu,Al)2H2Si2O5(OH)4*nH2O

FORMULA_HTML: (Cu,Al)₂H₂Si₂O₅(OH)₄•nH₂O

COLLECTION_LOCALITY: Miami, AZ

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Chrysocolla is a hydrogel or gelatinous precipitate.

"C-5 Chrysocolla 297B--Miami, Ariz. CuSi0₃nH₂0: Chrysocolla is a secondary mineral occurring in the oxidized zone of copper veins. The spectrum is dominated by the intense Cu²⁺ absorption near 0.75 µ, which together with the fall off in reflectivity to the blue, produces a reflectivity maximum near 0.5 µ and the blue green color of the mineral. Constitutional water produces the very intense 1.42 µ and 1.92 µ bands as well as the 2.23 µ feature."

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.

Grain size fractions are indicated by the extension after the sample number:
.1B = <5 µm
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Quartz - significant component
Chrysocolla - possible component
Note: Except for quartz this sample is amorphous. Chrysocolla is amorphous, therefore XRD is not a definitive test for chrysocolla.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:
90 vol% chrysocolla
10 vol% cryptocrystalline quartz

Light blue color, conchoidal fracture, fine fibrous crystal habit so optic sign cannot be determined (actually chrysocolla is amorphous so it would not have an optic sign). Soft. All consistent with chrysocolla. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # Chrysocolla HS297.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # Chrysocolla HS297.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3c4b # Chrysocolla HS297.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # Chrysocolla HS297.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns