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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: Buddingtonite GDS85 D-206 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS85 (D-206)

MINERAL_TYPE: Tectosilicate

MINERAL: Buddingtonite (Feldspar group)

FORMULA: (NH4)AlSi3O8*0.5H20

FORMULA_HTML: (NH4)AlSi3O8•½H20

COLLECTION_LOCALITY: Sulphur Bank, California

ORIGINAL_DONOR: Dennis Krohn, USGS Reston

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Reston (M. Dennis Krohn)

SAMPLE_DESCRIPTION:

Comment: there are weak bands at 1.4 and 1.55 µm. The 1.55 might be due to alunite. If so, the buddingtonite feature is more than 10 times stronger, so the buddingtonite 2.1-µm feature is probably spectrally pure. Similar arguments for the 1.4 band. If these features are due to buddingtonite itself, then it is even more spectrally pure. Roger N. Clark

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Quartz - major component
Buddingtonite - major component
No apparent alunite

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal Grain size distribution:
mode 1: 217 µm @ 5 vol%
mode 2: 12 µm @ 95 vol%

avg. gr sz = 50 µm (includes quartz)

mode:
75 vol% Buddingtonite
20 vol% quartz
5 vol% Fe-oxides

Buddingtonite has mottled extinction and is highly altered. Quartz forms larger grains. Most buddingtonite is polygranular with effective grain size around 40 µm. No HCl fizz. 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 744 0.2-3.0µm 200 g.s.= 50 µm
LIB_SPECTRA: splib05a r 1417 0.2-3.0µm 200 g.s.=


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