246 Ford — Remar'kdble Crystal of Apatite. 



The crystal measures 3*8^™ by 4'3'^'^ in the horizontal direc- 

 tions and S'^'" in the vertical direction and weighs slightly over 

 100 g. Its color is the wonderful deep amethyst characteristic 

 of apatite from this locality. The crystal contains cracks and 

 flaws and is cloudy in portions, but also in many small areas it 

 is perfectly clear and of a gem quality. The _crystal forms 

 observed include the following: c(OOOi), m(1010J', «(1120), 

 A^(3120), t(1016)_?, a^(101iy, 2/(2021), ^(3031), ^(1121), 

 /x(2l31) and />tj (3121). The accompanying figure represents 

 the crystal as nearly as possible in its true proportions and 

 about 1^ times its natural size. On one side of the crystal 

 there are several oscillations between the faces with conse- 

 quent parallel growth between different portions of the crystal. 

 Three of the edges between the base and the pyramid x are 

 replaced by narrow faces of a very low pyramid. These faces 

 are curved and do not yield a definite reflection on the goni- 

 ometer. The only known form that they might be, however, is 

 the pyramid t(1016). The faces of the pyramid ^, as is usual 

 on crystals from this locality, show marked horizontal stria- 

 tions and the prisms a and h^ commonly show faint vertical 

 striations. All of the other faces are plane with no distinctive 

 markings. Both the right and left forms of the third order 

 pyramid, />t and /x^, are present, with no apparent distinction 

 to be made between them in regard to their luster, etc. While 

 the figure shows the majority of the faces occurring upon the 

 crystal, several very small and narrow faces of the second and 

 third order pyramids had to be omitted from the drawing. 



A small crystal showing the same forms is attached at one 

 side to the lower part of the large crystal but is not represented 

 in the figure. A small amount of cookeite is attached to the 

 crystal. 



Mineralogical Laboratory of the 



Sheffield Scientific School of Yale University, 



New Haven, Conn., June 15, 1917. 



