Microprobe, laser mineral grains

Laser Microprobe Argon-39—Argon-40 Dating of Individual Mineral Grains... 

Conventional fluorination is usually done on 10-20 mg of whole-rock powder or minerals separated from much larger samples the inability to analyze small quantities means that natural heterogeneity cannot be detected by such bulk techniques. Recent advances in the development of laser microprobes, first described by Sharp (1990), have revolutionized mineral analyses. Laser techniques have both the resolution and precision to investigate isotopic zoning within single mineral grains and mineral inter- and overgrowths. 

Sutter J. F. and Hartung J. B. (1984) Laser microprobe "" Ar/ Ar dating of mineral grains in situ. Scan. Electr. Micros. 4, 1525-1529. 

In order to overcome these problems, interest was focussed on that portion of the organic matter trapped in mineral precipitates which formed synchronously with sedimentation. In these cases, the material is hermetically sealed in the crystalline matter and may survive with relatively little subsequent alteration. Such preservation is common in cherts which are chemical precipitates of silica and now comist of fine grained quartz. These rocks offer the best chance for successful preservation of truely Precambrian molecular fossils. Modem microprobes and spectrophotometer microscopes allow the non-destructive analysis of organic matter enclosed in mineral crystals. Laser bombardment of microscopic... 

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