TITLE: Hornblende HS16 DESCRIPT
MINERAL: Hornblende (Amphibole group)
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
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."
Sieve interval 74 - 250µm.
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.
40 kV - 30 mA, 7.3-9.5 keV
File: hnbld16.out, -.mdi
References: Borg and Smith (1969); Huebner's reference patterns
Found: clinamphibole, 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.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
75 vol% Hornblende
20 vol% Chlorite (basal cleav., 1st order gray, biaxial +)
5 vol% Plagioclase
avg gr size = 190 µm
Sample is significantly contaminated with other phases. Franz separator should work on this sample. Roger bets flat micas are pieces of hornblende, I say they are chlorite -- we bet a beer on this one. Hornblende has amphibole cleavage, strong green-blue pleochroism, OAP ll (010) ~ 30 degrees. All these properties are consistent with this being hornblende. Smaller > 10µm grains coat 10% of larger grain surfaces. G. Swayze.
LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 2196 0.2-3.0µm 200 g.s.= 190 µm
LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=