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: Howlite GDS155 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS155

MINERAL_TYPE: Borate

MINERAL: Howlite

FORMULA: Ca2B5SiO9(OH)5

FORMULA_HTML: Ca₂B₅SiO₉(OH)₅

COLLECTION_LOCALITY: Barstow, California

ORIGINAL_DONOR: Jim Piper

CURRENT_SAMPLE_LOCATION: USGS USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Howlite occurs as porcelaneous nodules in shale or, less commonly, silty sandstone, and as massive veins ranging from 2 to 30cm in thickness. - from Borates: Econ. Geol. & Prod., Barker and Lefond, eds. Proc. of Soc of Mining Eng, Oct 1984, Denver, p. 181.

Note howlite is very unusual in that it is the only mineral we know of with SiO₉.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA
Reference: JCPDS #35-630
Found: Howelite
Quartz sought but not found

Comment: Extraordinarily clear pattern, sharp peaks, excellent crystallinity.

J.S. Huebner and J. Pickrell, unpublished data, written communication, USGS, Reston, VA (1993)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_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 2218	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 3379	0.2-3.0µm	200	g.s.=

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