MINERALOGICAL NOTES — ANDERSON. 275 



" wachtums-figuren " described by Goldschmidt on the topaz 

 from the Thomas Range, Utah. 2 The prism faces in general 

 show a slight vertical striation. The dome d is striated somewhat 

 irregularly in a direction parallel to its intersection with o ; this 

 is not due to oscillatory combination, but to etching, and, now 

 and then, indications are seen of a definite etch-figure shaped 

 somewhat like a pear with the blunt end directed upwards. The 

 faces of y and /"inter-oscillate. 



Five crystals were measured on the two-circle goniometer ; 

 the mean angles obtained are tabulated below, together with the 

 calculated values given by Goldschmidt 3 (Dana's axes and lettering 

 are adopted). 



Of the doubtful faces iV and r were observed twice (images not 

 good), and it once each (images fairly good). 



•^Goldschmidt— Zeits. Kryst., xl., 1905, pp. 379, 382, pi. x., fig. 6b. 

 3 Goldschmidt — Krystallographische Winkeltabellen, 1897, pp. 346-348. 



