Author: Kayser, G. E.
Title: De cyclo quodam legum duodecim, secundum quas crystalli generum feldspathi familiae singulariorum geminatim coniunctae inveniuntur.
Description: Berolini, Nauck, 1834. 8vo (19.0 x 12.0 cm). 36 pp.; one folded engraved plate. Contemporary quarter cloth over marbled boards. Paper labels on the spine. = Rare thesis, defended by the mineralogist Gustav Eduard Kayser (1803-after 1863), on crystallography and in particular on twinning in the feldspar group. Twinning is the intergrowth of two or more grains of a given crystalline material according to some definite pattern or arrangement called a twin law. In this work, Kayser was the first to discovered and describe the twin law of feldspars. The importance of this thesis is underscored by the presence, among the opponents, of the then already influential German geologist and palaeontologist Friedrich August Quenstadt (1809-1889). Binding weak, vague library stamps on title and verso of title and in the text. Top part of the title restored, otherwise very good. Poggendorf I, 1233.

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