UNIVERSITY OF CALIFORNIA PUBLICATIONS 

 Bulletin of the Department of Geology 



Vol. 3, No. 2, pp. 31=50, Pis. 2=4. ANDREW C. LAWSON, Editor 



COLEMAN1TE 



FROM 



SOUTHERN CALIFORNIA. 



A DESCRIPTION OF THE CRYSTALS AND OF THE METHOD OF 

 MEASUREMENT WITH THE TWO-CIRCLE GONIOMETER. 



BY 



Arthur S. Eakle. 

 CONTENTS. 



PAGE „ 



Description of Crystals 31 



Introduction 31 



Elements » 33 



Forms 33 



New Forms - 35 



Crystal Habit 37 



Combinations 38. 



Projections 39 



Method 40 



Advantages -10 



Polar Orientation 41 



Symbols p q 42 



Gnomonic Projection 42 



Determination of e, H and P 43 



Determination of p and q'„ 43 



Determination of the Polar Elements p , q and e 44 



Determination of the Axial Lengths a and c 44 



Record of the Measurements 45 



Calculated Table : 48 



DESCRIPTION OF CRYSTALS. 



Introduction. — The mineralogical collection of the Univer- 

 sity of California includes several excellent specimens of 

 colemanite, showing beautiful crystals in the druses and 

 geodes of the massive material, and the abundance of good 



