130 Notices of Memoirs—Prof. Carvili Lewis—Matrixz of Diamond. 
to successive paroxysmal eruptions. A similar structure is known 
in meteorites, with which bodies this rock has several analogies. A 
large amount of the adjoining bituminous shale is enclosed, and has 
been more or less baked and altered. The occurrence of minute 
tourmalines is evidence of fumarole action. 
The microscopical examination supports the geological data in 
testifying to the igneous and eruptive character of the peridotite, 
which lies in the neck or vent of an old volcano. 
While belonging to the family of peridotites, this rock is quite 
distinct in structure and composition from any member of that group 
heretofore named. It is more basic than the picrite porphyrites, and is 
not holocrystalline like dunite or saxonite. It is clearly a new rock- 
type, worthy of a distinctive name. The name Kimberlite, from the 
famous locality where it was first observed, is therefore proposed. 
Kimberlite probably occurs in several places in Hurope, certain 
garnetiferous serpentines belonging here. It is already known at 
two places in the United States: at Elliott County, Kentucky, and 
at Syracuse, New York; at both of which places it is eruptive 
and Post-Carboniferous, similar in structure and composition to the 
Kimberley rock. 
At the diamond localities in other parts of the world aihmonds 
are found either in diluvial gravels or in conglomerates of secondary 
origin, and the original matrix is difficult 76 discover. Thus, in 
India and Brazil the diamonds lie in conglomerate with other 
pebbles, and their matrix has not been discovered. Recent observa- 
tions in Brazil have proved that it is a mistake to suppose that 
diamonds occur in itacolumite, specimens supposed to show this 
association being artificially manufactured. But at other diamond 
localities, where the geology of the region is better known than in 
India or Brazil, the matrix of the diamond may be inferred with 
some degree of certainty. ‘Thus, in Borneo, diamonds and platinum 
occur only in those rivers which drain a serpentine district, and on 
Tanah Laut they also le on serpentine. In New South Wales, near 
each locality where diamonds occur, serpentine also occurs, and is 
sometimes in contact with Carboniferous shales. Platinum, also 
derived from eruptive serpentine, occurs here with the diamonds. 
In the Urals, diamonds have been reported from four widely 
separated localities, and at each of these, as shown on Murchison’s 
map, serpentine occurs. At one of the localities the serpentine has 
been shown to be an altered peridotite. A diamond has been found 
in Bohemia in a sand containing pyropes, and these pyropes are 
now known to have been derived from a serpentine altered from a 
peridotite. In North Carolina a number of diamonds and some 
platinum have been found in river sands, and that State is dis- 
tinguished from all others in eastern America by its great beds of 
peridotite and its abundant serpentine. Finally, in northern Cali- 
fornia, where diamonds occur plentifully and are associated with 
platinum, there are great outbursts of Post-Carboniferous eruptive 
serpentine, the serpentine being more abundant than elsewhere 
in North America. At all the localities mentioned chromic and 
