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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: Actinolite HS315 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS315

MINERAL_TYPE: Inosilicate

MINERAL: Actinolite (Amphibole group)

FORMULA: Ca2(Mg,Fe+2)5Si8O22(OH)2

FORMULA_HTML: Ca2(Mg,Fe+2)5Si8O22(OH)2

COLLECTION_LOCALITY: Colorado

ORIGINAL_DONOR: Hunt and Salibury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Tremolite and Ferro-actinolite.

Original spectrum published in:

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.

With the note: "The very weak band near 0.63 µm indicates the presence of some ferric iron, which is often abundant in actinolites"

The spectrum in the library is sample HS315.4B which was dry sieved to the grain size interval 250-1200 µm.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV
File: actn315.out, *.mdi (smear mount on quartz plate)
References: Borg and Smith (1969); Huebner's reference patterns
Found: Clinoamphibole; trace of chlorite (?), talc, mica

Comment: Unusually large number of sharp reflections indicating excellent crystallinity and suggesting compositional homogeneity. Pattern is very similar to tremolite-actinolite from Ward's Creek, California, and the calculated tremolite pattern of Borg and Smith (1969). The identification of mica is based on one reflection (basal), of talc on the (002) and (004) reflections, and of chlorite on 2 ragged basal reflections. There is not a distinct 14 angstroms chlorite reflection. Coarser fraction than usual; was 4B used for spectroscopy?

J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994

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 57.72 wt% SiO2
COMPOSITION: TiO2 0.01 wt% TiO2
COMPOSITION: Al2O3 1.38 wt% Al2O3
COMPOSITION: Cr2O3 0.02 wt% Cr2O3
COMPOSITION: FeO 1.37 wt% FeO
COMPOSITION: MnO 0.33 wt% MnO
COMPOSITION: MgO 24.58 wt% MgO
COMPOSITION: CaO 13.27 wt% CaO
COMPOSITION: Na2O 0.37 wt% Na2O
COMPOSITION: K2O 0.09 wt% K2O
COMPOSITION: Total 99.14 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

EM analysis by Gregg A. Swayze at USGS Branch of Geophysics, Denver, Colorado.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Optical examination gives the following mineral mode:

96 vol% actinolite
3 vol% talc or mica
1 vol% Fe-stained pyrite?

Bimodal grain size distribution:

population 1 avg. grain size = 1000µm 99.9 vol%
population 2 avg. grain size = 30µm 0.1 vol%

avg. grain size all populations = 1000µm

Prismatic actinolite crystals with occasional pyrite? Inclusions altered to limonite and staining surrounding actinolite. Bundles of micaceous soft mineral resembles talc. Some actinolite grains (about 10 vol%) are polygranular, whereas most are single prisms bounded by cleavage faces. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_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 51 0.2-3.0µm 200 g.s.= 1000µm
LIB_SPECTRA: splib05a r 94 0.2-3.0µm 200 g.s.=


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