290 The Amenca7i Geologist. November, i90t> 
monium molybdate and sulphuric acid gave excellent tests for 
phosphoric acid and calcium respectively. 
The inclusions in this apatite are very various. They are: 
1. Solid. Besides the masses of orthoclase. hornblende, 
magnetite, and actinolite (see plate XVIII, Fig 12) introduced 
by corrosion there are: 
a. Dustlike particles, wholly irregular in shape and ar- 
rangement, usually rather sparingly, but evenly distributed. 
These are opaque and black; probably magnetite. 
b. Irregularly spherical particles frequently arranged 
along planes either transverse or curving and composed of 
magnetite. 
c. Acicular black inclusions having their long axis always 
parallel to the elongation of the apaatite. They are very 
minute, opaque and black, and probably composed of magne- 
tite. 
2. Cavities containing: 
a. A single liquid of high refringence, 
b. A single liquid of low refringence. 
c. A gas. 
d. A solid black particle (magnetite). 
e. Two liquids, one enclosed by the other, and possess- 
ing different indices of refraction. 
f. A liquid and a gas: the latter in the form of a bubble 
sometimes possessing rapid rotatory motion, and sometimes 
capable of displacement from side to side of the cavity. 
g. A liquid and a solid particle, apparently of magnetite. 
These cavities are usually nearly spherical; occasionally 
they show fantastic shapes, always curved. Thus, a sort of 
triple form is shown in figure 15A; an inclusion with a double 
border in figure 15B; and the curious case of two cavities con- 
nected by a sort of curved canal in figure 15C. 
The cavities are sometimes arranged along curving planes 
which are not however, the same planes as those containing 
magnetite particles ,but they are oftener scattered irregularl) 
through the whole crystal. Such inclusions, except the dusl 
particles, do not occur commonly in the other minerals of 
the rock. 
Finally, during the alteration of the rock, hematite and 
even biotite (see plate XVIII, Fig. 12), have penetrated into 
any fractures existing in the apatite. 
