CRYSTAL HABITS OF MINERALS.By Ivan Kostov and Ruslan I. Kostov. Bulgarian Academic Monographs (1), Prof. Marin Drinov Academic Publishing House and Pensoft, Sofia. 1999, 415 p. Hardback $65.00.
2001; Mineralogical Society of America; Volume: 86; Linguagem: Inglês
ISSN
1945-3027
Autores Tópico(s)Mineralogy and Gemology Studies
ResumoModern crystallography has its roots in curiosity, with attempts to answer the question of why one crystal species can take on a variety of external forms. In 1611, J. Kepler, fascinated by the elaborately varied dendritic forms of snowflakes, considered all snow crystals to be formed of close-packed equidimensional spheres even though the variety of forms ranged into the thousands. His observations marked the start of observational crystallography. In 1669, N. Steno formulated the law of constancy of interfacial angles, based on measurements from various prismatic forms of quartz that he had collected from mineral-filled alpine fissures. In his treatise, he explained the origin of varied polyhedral forms in quartz as a product of growth-rate anisotropy in different crystallographic directions. His concept of growth-rate anisotropy is the basis for modern studies of crystal forms. It is interesting to note that both structural crystallography and the science of crystal growth emerged from curiosity about the large variety in crystal forms. For mineralogists, this curiosity survives in attempts to derive meaning from crystal habit ( habitus or tracht in the German literature on this topic). Mineralogists have long been interested in the level of information that variation in habit may convey relating to growth and/or post-growth histories and …
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