THE PRINCIPAL FLOOR. 
78 
central belt of trap-rocks (diabase) traversed by copper-bearing 
veins. The metal is also found disseminated through the beds 
of trap, and through the sandstones and conglomerates ; and it 
likewise occurs in contact deposits between the diabase and the 
neighbouring rocks. The chief portion of the copper is native. 
This native copper contains a considerable proportion of silver ; 
but the two metals do not in general occur alloyed with each 
other, the silver being scattered through the copper in such a 
maimer that each metal remains chemically distinct from the 
other. ( See specimens in Case 22 .) 
There are also exhibited in this Case specimens of native 
copper, from the mines of Russia, Tuscany, Cuba, and Chile ; 
whilst of the valuable ore Cuprite or red oxide of copper ,, 
samples are exhibited from several localities in Russia, and from 
Rhenish Prussia, Hungary, Cuba, and South America. The 
detached crystals of cuprite from old workings at Chessy, near 
Lyons, are notable for their large size and perfect form, but 
the mineral is disguised by a thin coating of green carbonate. 
Case 16 . — The greater part of this case is occupied by 
specimens of the beautiful mineral Malachite or green carbonate 
of copper , of which the celebrated Russian deposits have con- 
tributed numerous fine examples. The richest masses of 
malachite have been found about 100 miles south of Bogoslovsk. 
Passing from the green to the blue carbonate of copper,. 
attention may be invited to the groups of finely-formed brilliant 
crystals from the now exhausted copper mines of Chessy, about 
20 miles N.W. of Lyons : from this famous locality the species 
has received the name of Chessylite. Some magnificent examples 
of the association of the blue and green carbonates are shown 
from the copper-mines of Arizona. 
The dark blaclush-green crystals of Libetkenite, a hydrous 
phosphate of copper, and the bright emerald-green Euchroite , a 
hydrous arsenate of copper, both from Libethen in Hungary, 
are placed by the side of some fine mammillated specimens of 
the cupreous phosphate called Ehlite , and a sample of the rare 
Russian mineral JDemidovite, a siliceous phosphate of copper. 
The mineral called Atcicamite, from Atacama, in South 
America, is an oxychloride of copper occasionally found in 
sufficient quantity to be worked 'as an ore, and occurring also 
as a volcanic product on certain Vesuvian lavas. 
In this case are also some fine specimens of Copper glance and 
bornite or purple copper ore , from the remarkable deposits of 
Monte Catini in Tuscany. These minerals occur, with other 
copper ores, in the form of nodules and irregular masses 
embedded in asteatitic matrix in a dyke of serpentine, or gabbro 
verde , associated with the rock called gabbro rosso. 
Case 17 . — On the upper shelves of this case are examples of 
Copper glance and purple ore from various localities, the fine 
masses of purple copper from Chile being especially noteworthy. 
The important German deposit of Kupferschiefer, or copper- 
slate, is represented by several specimens. This remarkable 
