Geology. 437 
in the period of the first fioetz -limestone. It probably ah 
so occurs in formations of a later date. 
19. Lead .— This metal occurs in the state of lead- 
glance, in beds, in primitive mountains in the Bannat of 
Temesvvar, but the quantity is so inconsiderable as not to 
entitle us to infer from this the high antiquity of lead. 
The beautiful crystallizations of white, green, yellow, and 
red lead-ores, are also insufficient for enabling us to ascer- 
tain this important point. It is lead-glance, the combi- 
nation of lead and sulphur, that affords the clew for de- 
termining the age of lead. That ore as we have already 
mentioned, occurs in inconsiderable beds in the primi- 
tive mountains in the Bannat of Temeswar ; in more con- 
siderable beds in the transition mountains of the Hartz ; 
but the greatest accumulation appears to be in beds in the 
oldest fioetz -limestone. Thus, the extensive mines of 
Tarnowitz, between the Oder and the Vistula, in Upper 
Silesia, contain great beds of lead- glance in the oldest 
fioetz -limestone. In Carinthia there is another great de- 
position of the same kind; and at Zimapan, in New 
Spain, great beds of lead-glance also occur in the same 
limestone formation. 
20. Zinc . — -This metal almost invariably accompa- 
nies lead, and either in the form of blende or calamine. 
The lead- glance veins in primitive and transition moun- 
tains are always accompanied with blende ; but the great- 
est quantity of this metal occurs in the state of Calamine, 
in great beds in the second fioetz -limestone, where it is also 
accompanied with lead-glance.* These beds of calamine 
occur in England, and extend through a considerable 
portion of Poland, Silesia, Westphalia, and the Nether- 
lands. 
* It has not been satisfactorily ascertained, whether these beds 
occur in the first or second floetz-limestpne , 
