The Microscope. 299 



Hanks said it has long been his opinion that if hydraulic mining had 

 been allowed to continue, a system of concentration would have been 

 adopted which would result in a larger production of gold and plati- 

 num and in the finding of more diamonds. At the present time we 

 know of the existence of diamonds in five counties in the State, as 

 follows: Amador, Butte, El Dorado, Nevada and Trinity. It is not 

 unlikely that they may yet be fovind in California more plentifully 

 than before. 



A very beautiful and remarkable diamond has lately come into 

 the possession of J. Z. Davis, a member of the Microscopical Society, 

 and this one Professor Hanks submitted for examination. It was 

 found in 1882 at Volcano, Amador county, by A. Schmitz. It weighs 

 0.361 grammes, or 5.570 grains, equal to 1.571 carats. It is a mod- 

 ified octahedron, about three-tenths of an inch in diameter, very 

 nearly if not quite colorless, perfectly transparent, but not without 

 some trifling inclusions and faults. The form of the crystal is 

 unusual. Professor Hanks has found such a one described or fig- 

 ured in books. The general form as shown by examination is that 

 of a regular octahedron, but the faces seem convex. The whole crys- 

 tal assumes a somewhat spherical form and the edges of the pyramids 

 are channels instead of planes, but on closer examination it will be 

 seen that the channeled edges, the convex faces and the solid angles are 

 caused by ari apparently secondary building up of the faces of a per- 

 fect octahedron, and for the same reason the girdle is not a perfect 

 square, but has a somewhat circular form. Ihese observations were 

 well shown by drawings exhibiting in enlarged form the outlines of 

 the gem. The faces seem to be composed of thin plates overlying 

 each other, and each slightly smaller than the last. These plates are 

 triangular, but the lines forming the triangles are curved, and the 

 edges of the plates themselves are beveled. Mr. Hanks remarked 

 further that it could be seen by the enlarged crystal shown under 

 the microscope, and by drawings exhibited, that each triangular plate 

 was composed of three smaller triangles, and that all the lines were 

 slightly curved. The building up of plate upon plate causes the 

 channeled edges and the somewhat globular form of this exquisite 

 crystal. The sketches shown were made fi'om the diamond, while in 

 the field of the microscope, by the aid of the camera lucida, being 

 enlarged about ten diameters. 



A close examination of the ciystal revealed tetrahedral impres- 

 sions as if the corners of minute cubes had been imprinted on the 

 surface of the crystal while in a plastic state. These are the result 



