468 On the Iron-pyrites Mines of Andalucia. | Oct., 
(4) A general order of succession and variation in the glacial 
deposits characteristically prevails both in Scottish and Norwegian 
localities, and embraces the phenomena of an epoch, rather than 
the merely subordinate accidents of local circumstance. 
III. ON THE IRON-PYRITES MINES OF ANDALUCIA. 
By A. H. Green, M.A., F.G:S., of the Geological Survey 
of England and Wales. 
For abundance and variety of ‘mineral products, scarce any land 
in the world can match Spain; but owing to the state of torpor 
into which this once active country has fallen, it has become all but 
a matter of impossibility to work her mines with profit. English 
and French capital and energy have, however, of late, in many in- 
stances, successfully battled with the difficulties of such an under- 
taking ; and among the districts thus opened out is a mineral tract 
reaching across the western part of Andalucia and the adjoming 
portion of Portugal, which contains many very large and remark- 
able deposits of Iron-pyrites. 
My own knowledge of this ground was gathered during rather 
a hasty visit, but I have been able to add to it from the works 
quoted below:* these, however, are but little known to general 
readers, and are besides of a somewhat technical character, and I 
therefore hope that the rather more popular account which I am 
undertaking may be neither unacceptable nor superfluous. 
The rock of the district is clay slate, Silurian in age,t bedded, 
but not cleaved ; taleose and micaceous slates are also met with, and 
here and there beds of quartzite. The strata rear up at very high 
angles, and are much contorted ; but I was told that a general north- 
easterly and south-westerly strike could be traced. Over the slate 
tract are scattered many “masses of porphyry of different kinds, 
passing here and there into diorites, accompanied at some points by 
masses of cupriferous iron-pyrites, which at the surface are repre- 
sented by deposits of oxide of iron, known in the country by the 
names of colorados, monteras de hierro, or requemones. ‘The por- 
phyritic masses are as a rule not very large, of small breadth, and 
* ‘Notes on the Copper Mining Districts of the Provinces of Seville and 
Huelva.’ By James Mason. London. 1858. 
‘Notes on the Mines of Rio Tinto.’ By J. Lee Thomas. London. 1865. 
‘Memoria sobre las Minas de Rio Tinto:’ presentada al Gobierno de S. M. 
Madrid. 1856. 
+ ‘Carte Géologique de Espagne et du Portugal.’ M. E. de Verneuil et 
E. Collomb. Paris. 1864. 
