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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: Hornblende HS177 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS177

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."

Sieve interval 74 - 250µm.

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.

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: EM(WDS) # XRF, EM(WDS), 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 (-), inclinded 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 Seperator and heavy liquids will probably separate out the hornblende. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_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 2208 0.2-3.0µm 200 g.s.= 190 µm
LIB_SPECTRA: splib05a r 3346 0.2-3.0µm 200 g.s.=


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