Paragonite

Spectrum Details

Modality

NIR

Category

mineral

Material Type

Phyllosilicate

Sample ID

GDS109

Collection Locality

Ilas de Margarita, Venezuela

Spectral Purity

1a2_3_4_ # GDS109 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

Composition / XRD

see discussion # XRF, EPMA, ICP(Trace), WChem

Sample Description

see: Robie, R.A., and B.S. Hemingway, 1984, Heat capacities and entropies of phlogopite and paragonite between 5 and 900 K and estimates of the enthalpies and Gibbs free energies of formation. American Mineralogist, v.69, pp. 858-868. IMAGE_OF_SAMPLE:

XRD Analysis

40 kV - 30 mA, 6.5-9.5 keV (smear mount of GDS109 = parag.out; smear mount of GDS109 ground with glass = parag2.out) References: Bailey (1988, p. 201); calculated 2M1 paragonite pattern of Borg and Smith (1969); Huebner's reference patterns Found: dioctahedral mica Sought but not found: quartz, muscovite, chlorite Comments: Many expected reflections were not resolved, even following grinding with glass; non-basal reflections are broad. The position of the (004) reflection indicates the presence of a small cation such as sodium. The polytype could not be determined. Even allowing for preferred basal orientation, GDS109 is poorly crystallized. It is not of the same quality as the "muscovites" and probably should not be compared with them to attempt to ascertain K/Na from spectra. However, poorly crystallized material such as GDS109 may be more representative of micas in sedimentary environments than is the suite of "muscovites". J.S. Huebner, J. Pickrell, and T. Schaefer, 1994, written communication. "Unit cell parameters are a = 0.5130±0.0010 nm, b = 0.8905±0.0017 nm, c = 1.9342&#177:0.0039 nm, and beta = 94.50.2° and the structure type is 2M1 (M.R. Ross, written communication, August 1982). These parameters are in good agreement with those reported by Chatterjee (1974) and Holland (1979) for synthetic 2M1 paragonite." Robie, R.A., and B.S. Hemingway, 1984, Heat capacities and entropies of phlogopite and paragonite between 5 and 900 K and estimates of the enthalpies and Gibbs free energies of formation. American Mineralogist, v.69, pp. 858-868.

X Units

cm⁻¹

Y Units

Absorbance

Data Points

2,126