Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, see: http://speclab.cr.usgs.gov)

TITLE: Lazurite HS418 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS418

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.

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, EM(WDS), 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: 1b2c3?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 2716	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 4087	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 12545			g.s.=
LIB_SPECTRA:	splib06a r 12557			g.s.=