Surface defects and microstructure in natural quartz crystals from Sierra Nevada (Spain)
ISSN: 0210-6558
Any de publicació: 1989
Volum: 12
Número: 0
Pàgines: 91-99
Tipus: Article
Altres publicacions en: Boletín de la Sociedad Española de Mineralogía
Resum
In the present paper, surface defects of quartz crystals from Sierra Nevada (Granada) are studied. The prismatic faces (1010) show the characteristic growth striations perpendicular to the [001] direction and the parallelogram shaped growth pyramid sextended in the direction which constitute such growth striations. Some of these faces, in which the local stress is very important, exhibit hexagonally shaped two-dimensional growth nuclei. Other characteristic features of these crystals are mainly grain boundaries more or less parallel to the [001] direction as well as vestiges of natural etching evidenced in different forms: etch pits, irregular cavities from other crystals and hexagonal depressions. The role of impurities in the growth mechanism is analyzed and the polycrystalline structure of these natural quartz crystals is shown.