MINERAL: Augite (Pyroxene Group, was listed as Diopside)
COLLECTION_LOCALITY: Hull, Ontario, Canada
ORIGINAL_DONOR: Wards Mineral Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
40 kV - 30 mA, 6.7-9.5 keV
File: dipsd588_mdi (smear on qtz plate)
References: Borg and Smith (1969); PDF2 #41-1370, 24-0201; Huebner's reference patterns and cell refinements, particularly that of diopside from Rotkopschart, Zillertal, Austria
Comments: Peaks are moderately sharp to sharp but the alpha1-alpha2 components are not well resolved. The high background is probably due to X-ray fluorescence (suggesting (Fe and/or Mn are present). All reflections can be indexed as clinopyroxene.
Identification was confirmed with profile-based search-match (ferroan augite, 24-0201). Lattice spacing's are larger than those of WS-592, HS-15, or synthetic end member diopside, yet smaller than those of hedenbergite HS-10. Conclude that this material is a clinopyroxene solid solution, not an end member diopside.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
Bimodal grain size distribution:
population 1 grain size = 450 microns at 80 vol%
population 2 grain size = 15 microns at 20 vol%
avg. grain size = 400 microns
Pure sample, inclined extinction, two cleavages at nearly right angles, pale green color, high order colors under cross-polarized light, biaxial (+), weak pleochroism, all consistent with augite. G. Swayze.
SPECTRAL_PURITY: 1b2c3b4b # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns