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Raman characterization of cored samples

prepared by minicoring device of Athena Payload

We analyzed twelve mini-cores of several rock types using a laboratory Raman system whose optical con-figuration is similar to the Mars Microbeam Raman Spectrometer (MMRS) [1]. The purpose is to establish the ability of the Raman spectrometer to identify min-eral phases under field-like conditions, i.e. on rough, broken surfaces placed at a fixed distance from the ob-jective without focusing the instrument before acquiring each spectrum.

The mini-cores did not break cleanly from the rocks, so some have considerable relief at their distal ends (Figure 1). Successful rock identification depends on an adequate depth of the Raman sampling field to obtain enough spectra to determine major minerals and their modal abundances. As a test, we made point counts [2] across the broken ends of the cores and compare them to point counts along the smoother sides of the cores.

core_image1.jpg (39981 bytes) core_image2.jpg (36912 bytes)
cross section of carbonate minicore

side view of carbonate minicore


The percent of spectra giving definitive mineral identification and the mineral proportions estimated from each traverse are given in Table 1. Table 2 shows the mineral proportions estimated using back-scattering electron images of two minicore samples.

core_table1.jpg (185882 bytes)


core_table2.jpg (48415 bytes)

Following are typical Raman spectra form these cored samples:

core_spec1.jpg (302507 bytes) core_spec2.jpg (364824 bytes)

References:  Kuebler, K.E., Wang A., Haskin L. A., Jolliff B. L., Characterization of mini-core samples using Raman point-counting, 32th LPSc, 2001.


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