Grossular

Spectrum Details

Modality

FTIR

Category

mineral

Material Type

Nesosilicate

Sample ID

HS113.3B-HCL

Collection Locality

Transvaal, S. Africa

Spectral Purity

1d2c3c4c # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

Composition / XRD

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

Sample Description

Forms series with Andradite, with Hydrogrossular, with Uvarovite. In this sample some ferrous ion has substituted for calcium, producing the 1.0 µm absorption and some ferric ion has substituted for aluminum, producing the band near 0.8 µm. Such substitution is common for this mineral. The presence of Fe accounts for the absorption features near 0.6 and 0.43 µm and the series of bands between 1.4 and 1.51 µm are due to OH substitution for SiO4. Carbonate impurities cause absorption features near 2.25, 2.35, and 2.5 µm. 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. Grain size fractions are indicated by the extension after the sample number: .3B = 74-250 µm See additional spectra of grossular garnets in library for comparison. This sample has been washed in HCl acid to remove carbonate contaminants. IMAGE_OF_SAMPLE:

XRD Analysis

Grossular + feldspar + others (Norma Vergo, USGS)

X Units

cm⁻¹

Y Units

Absorbance

Data Points

1,801