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: Vesuvianite HS446 Idocrase DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS446

MINERAL_TYPE: Cyclosilicate

MINERAL: Vesuvianite (Idocrase)

FORMULA: Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4

FORMULA_HTML: Ca₁₀Mg₂Al₄(SiO₄)₅(Si₂O₇)₂(OH)₄

COLLECTION_LOCALITY: Maine

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"S-6 Idocrase 446B--Maine. Ca₁₀(MgFe)₂Al_4- (SiO₄)₅(Si₂O₇)₂(OH)₄: Idocrase is found in crystalline limestones as a result of contact metamorphism. The spectrum displays a weak but well resolved ferrous iron band at 9.95 µ, a weak ferric ion band near 0.75 µ, and the typical associated fall off in reflectivity to the blue. Very well resolved hydroxyl doubled features occur near 1.4 and 1.44 µ, and the weak 1.9 µ feature indicates some H₂O. Combination OH bands occur near 2.2 and 2.37 µ. Note that these hydroxyl and water bands are located at their usual positions, unlike those displayed by other members of the epidote group. It is interesting that some authors (eg. Deer and others, 1963) do not include idocrase as a member of the epidote group, and the anomalous positions of its hydroxyl and water bands support this view."

Sieve interval 74 - 250µm.

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.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: idoc446.out, -.mdi (smear mount of coarse material on quartz plate) idoc446b.mdi (smear mount of finely ground material on quartz plate)
References: Borg and Smith (1969); JCPDS #38-437
Found: idocrase

Comment: Idocrase is well crystallized and appears to be the only phase. The pattern of coarse material shows anomalous intensities and some d-spacings of the smaller peaks are significantly shifted from the reference pattern. The pattern of fine material was refined (without internal standard) to a=15.603(4) and c=11.766(4) ; despite much peak overlap all observed reflections could be indexed using the calculated list of permitted d-spacings. J.S.Huebner, J. Pickrell, T.Schaefer, written communication (1994 USGS)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2a3a4a # 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 5148	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 7014	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 23527			g.s.=
LIB_SPECTRA:	splib06a r 23540			g.s.=