TITLE: Hedenbergite HS10 DESCRIPT
MINERAL: Hedenbergite (Pyroxene group)
COLLECTION_LOCALITY: Silver Star, Montana
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
Forms series with Diopside and with Johannsenite.
"S-17C. Pyroxene, variety Hedenbergite. Silver Star, Montana (10B). This sample has such strong ferric and ferrous ion bands on either side of 1µ that the reflectivity of the sample is reduced throughout the first half of the near-infrared range. Very weak water bands near 1.9 and 2.3 µ indicate the presence of some fluid inclusions. By contrast, a sample of artificially prepared hedenbergite displays a single strong ferrous ion band near 1.1 µ."
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.
40 kV - 30 mA, 7.3-9.5 keV
File: hedbg10.mdi, *.out (smear mount on quartz plate)
References: JSPDS#41-1372; Huebner's reference patterns
Found: Clinopyroxene consistent with hedenbergite, minor quartz, unindexed weak to very weak reflections at 8.6, 3.16, 3.11 angstroms
Comment: Clinopyroxene pattern that is distinct from that of diopside (such as HS-15.3B). Pyroxene reflections are not sharp, suggesting poor crystallinity or compositional heterogeneity. Quartz identification originally based on four weak reflections, subsequently confirmed by optics (n=1.545). Optically, many grains are discolored by brown, heterogeneously distributed material; the actual pyroxene grains are colorless by comparison. Does the optical spectrum see the pyroxene?
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
45 vol% red stained pyroxene
42 vol% clinopyroxene
10 vol% Mica
3 vol% Calcite
Green gains are pleochroic green with prismatic cleavage ( slight < 90 degrees) and slightly inclined extinction. Biaxial (+), moderate 2V, all consistent with clinopyroxene. Sample has a considerable number of grains which fizz in HCl indicating significant carbonate contamination of sample. I suggest a cleaner sample be obtained. G. Swayze.
LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 2006 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=