U.S. Geological Survey home page


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: Hectorite SHCa-1 AC-B DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: SHCa-1

MINERAL_TYPE: Phyllosilicate

MINERAL: Hectorite (Montmorillonite group)

FORMULA: Na0.33(Mg,Li)3Si4O10(F,OH)2

FORMULA_HTML: Na0.33(Mg,Li)3Si4O10(F,OH)2

COLLECTION_LOCALITY: San Bernadino, California

ORIGINAL_DONOR: Grim Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Trioctahedral lithium montmorillonite (stored in H20).

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Hectorite + quartz (m) + calcite (L) + dolomite (s)? (before acetate treatment) (Norma Vergo)

This sample was treated with acetate to dissolve carbonates. There is no fizz with HCl. Clay grains have sweeping extinction, quartz present but no evidence of calcite or dolomite. All consistent with a fairly pure sample of hectorite. G. Swayze.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: XRF # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 34.7 wt% SiO2
COMPOSITION: TiO2 0.038 wt% TiO2
COMPOSITION: Al2O3 0.69 wt% Al2O3
COMPOSITION: Fe2O3 0.02 wt% Fe2O3
COMPOSITION: FeO 0.25 wt% FeO
COMPOSITION: MnO 0.008 wt% MnO
COMPOSITION: MgO 15.3 wt% MgO
COMPOSITION: CaO 23.4 wt% CaO
COMPOSITION: Li2O 2.18 wt% Li2O
COMPOSITION: Na2O 1.26 wt% Na2O
COMPOSITION: K2O 0.13 wt% K2O
COMPOSITION: P2O5 0.014 wt% P2O5
COMPOSITION: F 2.60 wt% F
COMPOSITION: F 2.75 wt% F
COMPOSITION: S 0.01 wt% S
COMPOSITION: LOI 21.80 wt% LOI
COMPOSITION: Total 99.80 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE:

None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Mode:
99 vol% hectorite
1 vol% quartz
trace opaques (metallic luster)

Bimodal Grain Size Distribution:
mode 1: 204 µm @ 80 vol%
mode 2: 25 µm @ 20 vol%

average grain size = 183 µm

This sample was treated with acetate to dissolve carbonates. There is no fizz with HCl. Clay grains have sweeping extinction, quartz present but no evidence of calcite or dolomite. All consistent with a fairly pure sample of hectorite. 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 1974 0.2-3.0µm 200 g.s.= 183 µm
LIB_SPECTRA: splib04a r 1985 0.2-3.0µm 200 g.s.= 183 µm
LIB_SPECTRA: splib05a r 3126 0.2-3.0µm 200 g.s.=


USA.gov logo  Take Pride in America button