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: Lazurite HS418 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS418.1B, HS418.2B, HS418.3B, HS418.4B

MINERAL_TYPE: Tectosilicate

MINERAL: Lazurite (Lapis Lazuli) (Sodalite group)

FORMULA: (Na,Ca)7-8(Al,Si)12(O,S)24[(SO4),Cl2,(OH)2]

FORMULA_HTML: (Na,Ca)_7-8(Al,Si)₁₂(O,S)₂₄[(SO₄),Cl₂,(OH)₂]

COLLECTION_LOCALITY: Chile

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

(Na,Ca)_7-8(Al,Si)₁₂(O,S)₂₄[(SO₄),Cl₂Cl₂,(OH)₂(OH)₂] Beautiful blue.

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:

40 kV - 30 mA, 6.5-9.5 keV
File: lazur418.mdi (smear on quartz plate)
Reference: PDF2# 41-1393, 27-88
Found: Wollastonite 2M, lazurite or related species

Comments: Wollastonite peaks are very sharp and show clearly resolved alpha1 and alpha2 components, suggesting excellent crystallinity and compositional homogeneity. Lazurite peaks are very sharp, but not as strong as those of wollastonite. Profile-based search-match returned 2M wollastonite, hauyne and lazurite-C as probable hits. The intensities of the hauyne closely matched the non-wollastonite reflections; those of lazurite-C did not. Subsequent manual overlay of the six wollastonite patterns in the PDF2 database onto the non-sodalite-group reflections in HS-418 indicates that the wollastonite is of 2M, not 1A, structure type. Of the two 2M patterns in the database, the observed peak intensities better match 43-1460. Only six observed peaks lie clear of the numerous wollastonite peaks. These six peaks are explained by a primitive cubic lattice; the cell edge, 9.08 Angstroms, excludes sodalite but leaves other members of the sadalite group, nosean, lazurite, and hauyne, or their solid solution, as a possibilities (see Deer and others, 1962). The structure type could not be determined.

END_XRD_ANALYSIS.

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

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Wollastonite has weak spectral features and none can be detected in the spectrum of this sample.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # HS418.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS418.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2c3c4u # HS418.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS418.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns