HISTORY OF CRYSTALLINE ROCKS. 9 
small encrinites, the whole cemented by calcite. The pores of the crinoidal remains are 
filled by a peculiar silicate, which is well seen in sections or on surfaces etched by an 
acid. Surfaces thus treated show a congeries of curved, branching, and anastomosing 
cylindrical rods of the injecting mineral, sometimes forming a complete network, and ex- 
hibiting under a microscope coralloidal forms, with a white, frost-like, crystalline aspect 
resembling the variety of aragonite known as flos ferri. The same crystalline mineral, as 
observed by Dawson, occasionally fills the interstices between the larger fragments of 
organic forms in the limestone, and, as he observes, “ was evidently deposited before the 
calcite which cements the whole mass.” 
§ 5. The limestone in question is nearly pure, containing very little magnesia or iron- 
oxyd, and leaves, after the action of cold dilute chlorhydric acid, five or six-hundredths of 
insoluble residue, which is the mineral in question mixed with about one-fourth its 
weight of siliceous sand. The silicate is of a pale grayish-green color when seen in mass, 
and, losing water, becomes bright reddish-brown by calcination. It is partially decom- 
posed by strong heated chlorhydric acid, and completely by hot sulphuric acid, which dis- 
solves alumina, ferrous oxyd, magnesia, and smal] portions of alkalies, leaving flocculent 
silica, which is readily separated by a solution of carbonate of soda from the accompanying 
quartz-grains. Thus analyzed, the mineral, which under a lens appeared wholly crystal- 
line and homogeneous, save the accompanying quartz, yielded silica 38.03, alumina 28.88, 
ferrous oxyd 18.86, magnesia 4.25, potash 1.69, soda 0.48, water 6.91. The atomic ratio of 
this for protoxyds, alumina, silica and water is very nearly 1:2: 3:1, which, abstracting 
the water, is that of zoisite ; the hydrous silicate jollyte being 1:2:3:2. Ihave given to 
this crystalline silicate, which is of curious interest alike for its composition and the mode 
of its occurrence, the name of hamelite for the Rev. Dr. Hamel, Rector of Laval University, 
Quebec. ! 
$ 6. The second silicate above referred to is not unlike hamelite in its characters and 
manner of occurrence, though differing somewhat in atomic ratios. It was found in a 
mass of fossiliferous limestone said to be from a locality in the island of Anglesea, and in- 
cluding, “besides a small coral-like body referred to the genus Verticillopora, joints and 
plates of crinoids, small spiral gasteropod shells, with fragments of brachiopods, and a 
sponge-like organism with square meshes.” All of these organic forms are more or less 
penetrated with a greenish silicate, which fills the cavities of the gasteropods, the central 
canal of the crinoids, and the pores of the Verticillopora. It has also replaced, or filled, 
the spongy fibres, and injected the minute cells of some of the crinoidal fragments, though 
many of these are solid throughout, in which respect the specimen differs from that from 
New Brunswick described above, where the infiltration of the crinoidal remains is much 
more complete and perfect. Sir J. W. Dawson, to whom we owe these observations, sup- 
poses that in both cases the infiltration took place while the remains were still recent 
§ 7. Decalcified surfaces of this limestone from Anglesea show similar appearances to 
those presented by the New Brunswick specimen, and the casts of the gasteropodous 
shells, two millimetres in length, are in some cases perfect. The limestone is nearly pure, 
with the exception of a little fine yellow ochreous matter which is insoluble in dilute 

‘Amer. Jour. Science, 1871, i. 379; also J. W. Dawson, The Dawn of Life, pp. 120-123, with figure of a portion 
of infiltrated crinoid on p. 103, 
Sec. IIL, 1886. 2. 
