Maghemite

Spectrum Details

Modality

NIR

Category

mineral

Material Type

Oxide

Sample ID

GDS81

Collection Locality

Synthetic

Spectral Purity

1b2b3b4_ # GDS81 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

Composition / XRD

None # XRF, EPMA, ICP(Trace), WChem COMPOSITION_TRACE:

Sample Description

This sample is one of a series of sample synthesized for the following paper: Sherman, D.M., R.G. Burns, and V.M. Burns, 1982, Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy. Journal of Geophysical Research, v. 87, n. B12, pp. 10169- 10180. Maghemite is formed either by the oxidation of magnetite or by the thermal dehydration of lepidocrosite. The spectrum of our sample, M-3 most closely matches the spectrum of sample M-4A in the above paper. M-4 was produced by thermal oxidation of magnetite. The Mossbauer spectrum of that sample showed no evidence of a magnetite component. The X-ray patterns confirmed the identity of the sample and the TEM data indicated that the sample was well crystallized. IMAGE_OF_SAMPLE:

XRD Analysis

40 kV - 30 mA, 7.3-9.5 keV File: maghmt81.out, -.mdi References: Maghemite C (JCPDS 39-1346), Maghemite Q (JCPDS 12-1402) and Magnetite (Huebner's reference patterns). Found: maghemite C, maghemite Q and/or magnetite; quartz Comment: 5 very broad, very weak reflections correspond to a very poorly crystallized oxide phase, but the X-ray powder pattern does not reveal which one. The brown color suggest that magnetite, if present, is minor. Five reflections of quartz; the (100) and (101) are very sharp, suggesting well-crystallized quartz, rather than a precursor. Quartz may have been added as a peak reference for XRD analysis by D. Sherman

X Units

cm⁻¹

Y Units

Absorbance

Data Points

2,126