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Crystals of pentachloronitrobenzene are rhombohedral, space group R3, with cell dimensions: ahex = 8-751 (2), Chex = 11"111 (5)/~ and three molecules in a hexagonal cell. The structure was determined by a three-dimensional X-ray analysis. The final R value was 0.107 for 225 observed reflexions. Diffraction patterns showed a partial enhancement of symmetry. The crystal has a disordered structure with an apparent molecular symmetry i~. The positions of the nitro groups overlap those of one of two crystallographically non-equivalent chlorine atoms. The nitro group has two orientations about the C-N axis. The angle between the plane of nitro group and that of the benzene ring is 62 ° .

Lattice impurities (Al, Li, Fe) free from the influence of cations in inclusion liquid were evaluated by atomic absorption spectrophotometry (AAS) in quartz lascas taken from 10 deposits with known localities in three states, Minas Gerais, Tocantins and Bahia. Levels of Al content and associated Li content depend on the localities of deposits. Quartz deposit regions with high Al content are composed of granite, gneiss, and pegmatite as surrounding rocks. It was concluded that the charge compensation for Al-Si substitution in quartz lascas was realized substantially by the formation of Al-Li and Al-OH centers which were confirmed from the linear relation of Al-Li plots by AAS data and IR spectra due to Al-OH center. The variety in Al-Li and Al-OH correlations was attributed to the fluctuation of growing conditions of quartz in nature.