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: 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)2Al4- (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 et al., 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.

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 intensitites 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: 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 5148 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 7014 0.2-3.0µm 200 g.s.=


USA.gov logo  Take Pride in America button