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: Magnetite HS195 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS195

MINERAL_TYPE: Oxide

MINERAL: Magnetite (Spinel group)

FORMULA: Fe+2(Fe+3)2O4

FORMULA_HTML: Fe⁺²Fe⁺³₂O₄

COLLECTION_LOCALITY: Ishpeming, Michigan

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms a series with Magnesioferrite and with Jacobsite.

The spectrum of this sample was originally published in:

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: III. Oxides and hydroxides. Modern Geology, v. 2, p. 195-205.

With the note: "This sample is slightly contaminated with (spectrally neutral) quartz. Like the previous sample [HS78], it displays typically opaque behavior, decreasing in reflectivity with decreasing particle size. It is unusual in that it also exhibits a very weak band near 1.0µm due to the ferrous ion. The explanation for its opacity is as given above for [Magnetite HS78]."

The sample measured for the library was HS195.3 which was dry sieved to the grain size interval 74-250µm.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: magnti195.out, -.mdi, ground once; mgt195-2.*, ground twice
References: JCPDS 19-629; Huebner's reference patterns; SEM X-ray spectroscopy.
Found: Magnetite, traces of an alkali feldspar (albite?), chlorite, and an unidentified phase with reflections at 3.31, 3.13, and 3.05 Angstroms.

Comments: Magnetite is well crystallized and peak compositions are consistent with Fe3O4 composition. SEM suggests grains containing Ca-Mn-Mg-Fe (carbonate?).

END_XRD_ANALYSIS.

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

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4_ # 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 2864	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 4243	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 13178			g.s.=
LIB_SPECTRA:	splib06a r 13189			g.s.=