Siderite

Spectrum Details

Modality

FTIR

Category

mineral

Material Type

Carbonate

Sample ID

HS271.1B, HS271.2B, HS271.3B, HS271.4B

Collection Locality

Roxbury, Connecticut

Spectral Purity

1a2_3_4_ # HS271.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns SPECTRAL_PURITY: 1a2_3_4_ # HS271.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns SPECTRAL_PURITY: 1a2a3a4_ # HS271.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns SPECTRAL_PURITY: 1a2_3_4_ # HS271.4B # 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

Forms series with Magnesite and with Rhodochrosite. "C-7. Siderite. Roxbury, Conn. (68, hand-ground). Siderite, FeCO3, is found in extensive sedimentary beds, frequently contaminated with clay or organic matter. It is also commonly deposited in veins by hydrothermal solutions. Both magnesium and manganese commonly substitute for the iron. This particular sample is coarsely crystalline and medium brown in color. It is high in iron, as indicated by the strong ferrous ion band near 1.1µ. It is also slightly contaminated with magnetite. Being an opaque material, the magnetite lowers the overall reflectivity of the sample, makes the carbonate bands less prominent, and causes the crossover of the spectral curves in the visible. Analysis shows that this sample contains 0.98% Mg^2+ and 7.03% Mn^+2. However, the electronic transitions of iron dominate the spectrum to such an extent that none of the sharp features due to Mn^++ are apparent in the visible spectrum." NOTE: This a different sample number than this sample (271) but the collection locality is the same. Possibly a mislabeled sample. Hunt, G.R., J.W. Salisbury, 1971, Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Modern Geology, v. 2, p. 23-30. Grain size fractions are indicated by the extension after the sample number: .1B = IMAGE_OF_SAMPLE:

XRD Analysis

Pure siderite Possibly some manganoan siderite also - patterns too similar to differentiate. Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

X Units

cm⁻¹

Y Units

Absorbance

Data Points

1,801