488 APPENDIX. No. VI. 
Capt. Tuckey, and affixed to one of them from the highest summit, informs 
us that a globule of some metal, either gold or copper, has been seen adhering 
to one of the cavities, by Dr. Smith; but no such observation has been com- 
municated in this Gentleman’s journal: the lump, however, bears evident 
marks of having been exposed to the action of fire. There is scarcely any 
appearance of metals in the rocks near the lower parts of the Zaire; if, there- 
fore, the accounts which the missionaries have given of the great abundance 
of every description of ores in Congo, extend to the banks of that river, it 
must be higher up; where, according to Dr. Smith’s account, the rock-for- 
mation appears to adopt a different character. The specimens from Condo- 
Sono, Banza Nokki, and Benda consist of sienite, with green hornblende, and 
a rock composed of feldspar and quartz, with thickly-disseminated particles of 
magnetic iron stone, instead of mica or hornblende. It is probable that the 
primitive trapp occurs here in beds subordinate to the gneiss and mica-slate, 
of which a few specimens are sent, together with some others from the same 
parts, which appear to be flint-slate. ; 
A rolled piece of sienite from the falls of Yellala, covered by a thin, 
shming, black crust, proves, that the action of the water of the Zaire is similar 
in its effects to that of the Oronoko. There are boulders of sienite im our 
collection, found by Baron Humboldt, at the cataracts of Alures, which are 
covered with exactly the same crust, and bear, externally, the most striking 
resemblance to meteoric stones. This black crust, both im the stones from the 
Zaire, and from.the Oronoko, Mr. Children, to whom I communicated some 
particles, found to be a mixture of oxides of iron and manganese. 
There are no specimens sent from above the Falls, except two varieties of 
compact limestone, one of them magnesian; but the places from which they 
came are not distinctly marked. : 
: This is all I have to say on the scanty materials before me; and I leave it 
to you to make any use of it you please. Believe me, my dear Sir, 
Your most obedient humble Servant, 
CHARLES KONIG. 
To John Barrow, Esq. Sec. to 
the Admiralty, &c. &. &e. 
