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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_Fe HS115 Amphibole DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS115

MINERAL_TYPE: Inosilicate

MINERAL: Ferro-Hornblende (Amphibole group)

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

FORMULA_HTML: (Mg,Fe)2Mg5Si8O22(OH)2

COLLECTION_LOCALITY: Brewster, 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-1E. Amphibole, variety Hornblende. Brewster, N.Y., (115B). This is an impure sample, deep green in color. It displays the double band structure in the 0.6 to 1.1 µ region that is typical of the presence of both the ferric and ferrous ion. The presence of a light gray contaminant (muscovite) raises the reflectivity of the sample which is most obvious in the largest size range, and explains the anomalous (lighter?) reflectivity of that size fraction. The hydroxyl bands are not so strong as in tremolite and actinolite, which is typical of hornblende. The very weak bands in the visible near 0.5, 0.45, and 0.5 µ are due to both the ferrous and ferric 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.

Sieve interval 74 - 250µm.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: hnbld115.out, -.mdi
References: Borg and Smith (1969)
Found: Clinoamphibole, minor mica, trace chlorite

Comment: Pattern matches that of tremolite more closely than hornblende.

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

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE:

None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:

90 vol% Hornblende
8 vol% plagioclase + quartz + other (uniaxial -)
1 vol% mica (clear)
1 vol% calcite (fizz with HCl)

average grain size = 250 µm

Smaller grains ~5 µm coat larger grains @ 30% surface area. Hornblende has inclined extinction (19 ° for OAP ll (010)), biaxial (-), strong green-blue pleochroism, and amphibole cleavage. All these properties are consistent with this sample being mostly hornblende. Heavy liquid or Franz separation may sort impurities out. 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 2185 0.2-3.0µm 200 g.s.= 250 µm
LIB_SPECTRA: splib05a r 3357 0.2-3.0µm 200 g.s.=


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