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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

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

TITLE: Axinite HS342 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS342

MINERAL_TYPE: Cyclosilicate

MINERAL: Axinite (Axinite group)

FORMULA: (Ca,Mn,Fe+2)3Al2BO3Si4O15(OH)

FORMULA_HTML: (Ca,Mn,Fe+2)3Al2BO3Si4O15(OH)

COLLECTION_LOCALITY: Mexico

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"(Ca, Fe2+, Mn)3Al2(BO3)(Si4O12)(OH): Axinite is found in contact-altered calcareous rocks and in hydrothermal veins. Its spectrum reveals iron bands in the visible and an extremely intense feature centered near 1.2µm, together with a broad feature to longer wavelengths."

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, vol. 4, pp 85-106.

74-250µm sieve interval.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: axint342_mdi, *.out (smear mount on quartz plate)
References: JCPDS #29-344, 27-76, 6-444, 27-84; Huebner's reference patterns
Found: mineral of axinite group; very weak reflections at 2.86, 2.12, 1.95, and 1.755 angstroms
Sought but not found: actinilite, andradite, biotite, calcite, datolite, epidote, feldspars, fluorite, hedenbergite, laumonite, prehnite, pyrite, quartz, tourmaline, zoisite

Comment: Very sharp reflections indicate excellent crystallinity. Members of the axinite group have similar unit cell dimensions. Based on peak positions, we suggest that HS-342 is ferroaxinite, tinzenite, or manganaxinite, but not magnesioaxinite.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

No compositional analyses available

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Optical examination gives the following mineral mode:

99 vol% axinite
1 vol% wh. mica?

avg. grain size = 330µm

Flaky fractured axinite grains with faint pink color. One distinct cleavage, high relief, inclined extinction, and (-) biaxial with 2V=40/(de. All these optical properties are consistent with axinite. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_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 625 0.2-3.0µm 200 g.s.= 330 µm
LIB_SPECTRA: splib05a r 1274 0.2-3.0µm 200 g.s.=


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