Evaluation of rock powdering methods to obtain fine-grained samples for CHEMIN, a combined XRD/XRF instrument

Conference · Thu Jan 01 04:00:00 EST 2004

OSTI ID:977406

Chipera, S J ^[1]; Vaniman, D T ^[2]; Bish, D L ^[3]; Sarrazin, P; Feldman, S; Blake, D; Bearman, G H ^[4]; Bar-Cohen, Yoseph

---

1. Steve J.
2. David T.
3. David L.
4. Gregory H.

A miniature XRD/XRD (X-ray diffraction/X-ray fluorescence) instrument, CHEMIN, is currently being developed for definite mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument produces good results even with poorly prepared powder, the quality of the data improves and the time required for data collection is reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD reuslts from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, they compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRD instrument such as CHEMIN.

• Research Organization: Los Alamos National Laboratory
• Sponsoring Organization: DOE
• OSTI ID: 977406
• Report Number(s): LA-UR-04-0286; LA-UR-04-286
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BENCHMARKS
EVALUATION
FLUORESCENCE
GRAIN ORIENTATION
GRAIN SIZE
SAMPLE PREPARATION
SAMPLING
SOILS
TUNGSTEN CARBIDES
X-RAY DIFFRACTION