Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, 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

IMAGE_OF_SAMPLE:

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Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.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.=
LIB_SPECTRA:	splib06a r 3924			g.s.=