380 J. D. Dana on Serpentine Pseudomorphs 
3. Hexagonal prisms, probably after Apatite. 
These prisms occur imbedded in the cubic serpentine. They 
are slender, being less than a line in diameter. By measure- 
ment, they are regular hexagonal prisms; and as apatite is one 
of the occurring minerals of the mine, they are probably pseu- 
domorphs after that species. 
Relations of the Cubic to the Hexagonal Pseudomorphs, and to the 
associated Minerals. 
(1.) In the specimen, a portion of which is represented in 
fig. 1, the cubical portion rests upon the coating of the rhombo- 
hedral portion; and over a large part of the specimen the 
former is easily separated, and leaves exposed the shining sur- 
face of the latter. Only in a small part are the two soldered 
together. The prismatic pseudomorph in view has been ex- 
posed by such a removal. 
It is thus demonstrated that the group of large hexagonal 
ponte preceded the existence of the cubical portion. e 
ence discover that the following was the order of events. 
1. The crystallization of a group of hexagonal prisms, prob- 
ably of calcite. 
2. The change of these crystals to serpentine and partly to 
dolomite. 
8. The incrusting of these prisms, after this change, by ser- 
penutine, making a coating over the whole, as shown in figure 1. 
4. The deposition, over this coating, of a cubic mineral whose 
masses had many cubic cleavage-joints. : 
5. The change of the cubic mineral to dolomite, by infiltra- 
tion along the open cleavage joints, and hence with a retention 
of many cubic cleavage surfaces aoe 
6. The change of part of the dolomite, thus cubic in cleav- 
age surfaces, to serpentine, through the infiltration along the 
cleavage-joints of a solution of magnesia-silicate, the alteration 
affecting entire rectangular blocks or plates of the dolomite, 
but leaving throughout adjoining blocks or plates unaffected. 
Thile proving here that there were an earlier and a later era 
of pseudomorphism, it is not proved that the successive eras may 
not have been comprised within a single epoch of pseudomor- 
phism. They may have been successive events in a single 
month or year. 
(2.) With regard to the relations of the pseudomorphs to the 
associated minerals, we note: 
In an olive-green specimen of the cubic serpentine there 
are imbedded tabular crystals of chlorite (ripidolite), and also 
__ large dodecahedral crystals of magnetite. Along with these 
_ Ininerals occur the pseudomorphs after apatite. 2 
_ This association proves either that the crystals of chlorite 
_ and magnetite were formed at the time the original cubic min- 
