U.S. Geological Survey home page

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
For more information on the library, see: local link web link

TITLE: Axinite HS342 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS342.1B, HS342.2B, HS342.3B, HS342.4B, HS342.6

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.

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
.6 = cut slab

IMAGE_OF_SAMPLE:
Photo of sample

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: actinolite, andradite, biotite, calcite, datolite, epidote, feldspars, fluorite, hedenbergite, laumontite, 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, EPMA, 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_ # HS342.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS342.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2c3b4b # HS342.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS342.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS342.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns