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: Hornblende HS16 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS16.2B, HS16.3B, HS16.4B, HS16.6

MINERAL_TYPE: Inosilicate

MINERAL: Hornblende (Amphibole group)

FORMULA: Ca2(Mg,Fe+2)4Al(Si7Al)O22(OH,F)2

FORMULA_HTML: Ca₂(Mg,Fe⁺²)₄Al(Si₇Al)O₂₂(OH,F)₂

COLLECTION_LOCALITY: Ontario

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series from Magnesiohornblende to Ferrohornblende.

"I-22 Hornblende 16B--Ontario. (Ca, Na₉K)_2-3- (Mg, Fe²⁺, Fe³⁺, Al)₅(Si₆(Si, Al)₂O₂₂)(OH, F)₂: Hornblende is the name given to a very complex series which varies with respect to at least ten major components. This spectrum is quite typical of hornblende spectra, which display a rapid fall off in intensity from 2.0µ to the blue due to broad Fe²⁺ and Fe³⁺ absorption near 0.7µ and 1.0µ. The hydroxyl band at 1.4 is also reduced in intensity or missing, leaving only OH features at 2.33µ and 2.4µ."

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:
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm
.6 = cut slab

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: hnbld16.out, -.mdi
References: Borg and Smith (1969); Huebner's reference patterns
Found: clinoamphibole, K-mica, trace chlorite (?), unindexed reflections at 3.02, 2.09, and 2.06 Angstroms

Comment: The clinamphibole patterns is consistent with that of hornblende.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE:

None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Mode:
75 vol% Hornblende
20 vol% Chlorite (basal cleavage, 1st order gray, biaxial +)
5 vol% Plagioclase
trace Garnet

average grain size= 190 µm

Sample is significantly contaminated with other phases. Franz separator should work on this sample. Hornblende has amphibole cleavage, strong green-blue pleochroism, OAP ll (010) ~ 30 degrees. Micas likely present. All these properties are consistent with this being hornblende. Smaller > 10µm grains coat 10% of larger grain surfaces. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # Hornblende HS16.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2c3b4_ # Hornblende HS16.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # Hornblende HS16.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # Hornblende HS16.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns