name mineral opened closed years connected notes
name
mineral
opened
closed
years connected
notes
number parsed year
number parsed year
minimum_number minimum_parsed minimum_year maximum_number maximum_parsed maximum_year
text text date date timespan text
blaen y cwm slate 1820 1911 1876-1911 connected to the ffr via the rhiwbach tramway
the ffestiniog railway serviced at most how many slate quarries ?
DT NNP NNP VBD IN JJS WRB JJ NN NNS .
20
select count ( * ) from w where c2 = 'slate'