Intensive efforts have been made to understand metamictization of minerals for the last ten years by using modern techniques such as transmission electron microscopy, infrared spectroscopy, X-ray absorption spectroscopy, Rutherford backscattering spectrometry. Ion-bombardment and short half-life actinide doping have been successfully applied to the studies of metamict minerals.This paper reviews data on metamict minerals and materials recently accumulated. Metamictization, the alpha-decay induced transformation from a periodic, crystalline mineral to an aperiodic, metamict mineral occurs in a very narrow range of alpha-decay dose (e.g., between 10¹⁵ and 10¹⁶ alphadecay events/mg in zircon). The damage ingrowth process can be divided into three stages: In Stage I, the mineral is essentially crystalline, with an expansion of the unit cell, a decrease in the Bragg diffraction intensity and an increase in the strain, which are caused mainly by the interstitial defects. Isolated, aperiodic domains resulting from alpha-recoil tracks are seen, but small in amount. Alpha-particles play a main role in the metamictization in Stage I. In Stage II, the damage ingrowth is characterized by a significant increase in the aperiodic domains resulting from alpha-recoil tracks. The crystalline domains become smaller in volume and size. In Stage III, the mineral is essentially X-ray and electron diffraction amorphous, and does not have any long-range periodicity. The decrease in the density through Stages II and III suggests a variation in the structure of the aperiodic region, the metamict structure.

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A multifunctional spectroscopic method under a polarizing microscope has been introduced. The polarizing microscope spectrophotometer is an assembled form that consits of a standard polarizing microscope attached with epi-illuminators (Hg or Xe or YAG), monochromaters, photodetection systems (photo-multiplier with Lockin amplifier or Boxcar digital processor, or diode array optical multi-channel analyzer) and a microcomputer. However it is restricted to the visible light region. Some effectiveness of this system have been demonstrated: Weak pleochroism in the absorption spectra and enhanced photo-luminescences originated from the same center as occur in the absorption are sensitively detected in zircon. Absorptiometry of ion exchange resin phase absorbing Cr⁶⁺ ions as colored species from aquious solution is successfully performed with sensitivity in two orders of higher magnitude than a conventional method.

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This article demonstrates the method of simple hot-filament-assisted chemical vapor deposition (CVD) for diamond growth. In this method, a tungsten filament at 2000 to 2350°C is used to dissociate gas mixtures containing about 3 vol% C₂H₂OH in H₂. The filament is typically placed within 2 mm of the surface of a molybdenum substrate to produce diamond. Diamonds grown by this method are commonly bounded by cubic {100} or depressed octahedral {111} planes or combination of the two.

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