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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: Hornblende HS177 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS177.1B, HS177.3B, HS177.4B, HS177.6

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: Gore Mtn, New York

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.

"S-1G. Amphibole, variety Hornblende. Gore Mountain, N.Y. (177B). This sample is exceptionally pure hornblende. As in samples S-1E and S-1F, note weakness of hydroxyl bands and general low reflectivity throughout, but particularly to shorter wavelengths, due to the presence of abundant ferric and ferrous ions."

Hunt, G.R., J.W. Salisbury, 1970, Visible and near-infrared spectra of minerals and rocks: I. Silicate minerals. Modern Geology, v. 1, p. 283-300.

"Results of petrographic examination: Specimen is a cluster of very dark green single crystals half a centimeter to one centimeter in length and almost as wide."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Grain size fractions are indicated by the extension after the sample number:
.1B = <5 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: hnbld177.out, -.mdi
References: Huebner's reference patterns
Found: clinoamphibole, K-mica, K-feldspar, Na-feldspar, clinopyroxene,unindexed reflection at 2.1 Angstroms.

Comment: The clinoamphibole pattern is consistent with hornblende. All reflections are sharp, suggesting good crystallinity and compositional heterogeneity.

J.S. Huebner, J. Pickrell, T. Schaefer, written communication(USGS)

Hornblende + trace other (Norma Vergo).

"Hornblende + trace of unidentifiable mineral."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EPMA # XRF, EPMA, ICP(Trace), WChem


COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 41.50 wt% SiO2
COMPOSITION: TiO2 2.89 wt% TiO2
COMPOSITION: Al2O3 12.97 wt% Al2O3
COMPOSITION: FeO 15.43 wt% FeO
COMPOSITION: MnO 0.13 wt% MnO
COMPOSITION: MgO 11.49 wt% MgO
COMPOSITION: CaO 11.34 wt% CaO
COMPOSITION: Na2O 1.61 wt% Na2O
COMPOSITION: K2O 1.71 wt% K2O
COMPOSITION: Total 99.08 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

"Microprobe analysis shows the sample to be homogeneous within and between grains. Average of 10 grains."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Mode:
77 vol% Hornblende
15 vol% Biotite? (biaxial -, brown, low 2v)
6 vol% Other amphibole
2 vol% plagioclase (twinning)

average grain sz = 190 µm

Hornblende has amphibole cleavage, strongly brown pleochroic, OAP ll (010) = 10 degrees, biaxial (-), inclined extinction. All these properties are consistent with hornblende. Biotite or brown mica has basal cleavage, low 2v, and biaxial (-). Other prismatic amphibole? This mineral is clear, non-pleochroic, high order color, biaxial (+), inclinded extinction. Although this sample is contaminated, a combination of Franz Separator and heavy liquids will probably separate out the hornblende. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_3_4_ # Hornblende HS177.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2b3b4_ # Hornblende HS177.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Hornblende HS177.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Hornblende HS177.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns