Original paper
Morphogenesis of quartz crystals twinned after Japan Law
Sunagawa, Ichiro; Imai, Hiroyuki; Takada, Masayuki; Hoshino, Yukio
European Journal of Mineralogy Volume 16 Number 1 (2004), p. 91 - 97
published: Feb 23, 2004
Abstract
Why quartz crystals twinned after Japan Law take flattened morphology and grow larger than the co-existing single crystals is explained based on the results of previous morphological, X-ray topographic and re-growth experimental data. It has been concluded that Japanese twin is a contact twin, and the characteristic V shape represents the upper half of a Y shape and not opposing half of an X shape. In a new locality, Japanese twins of X shape or doublet and triplet of X shapes are found, which opens a question to the validity of the above model. In this locality, unusually high proportion of quartz crystals, more than 90 %, are twinned. Investigation of the samples from this locality revealed that the apparent X shape is a result of a combination of two Y shapes, indicating that the above model is valid in this case as well.
Keywords
quartz twinning • japan law • apparent re-entrant corner effect • contacttwin vs penetration twin • single doublet and triplet of x-shape morphogenesi