Table:
text: List of quarries served by the Ffestiniog Railway
The quarries
The quarries
Name_ Mineral Opened Closed Years_connected Notes_
Cwmorthin Slate 1810 1937 1850–1937 Connected via the Cwmorthin Tramway; became part of the Oakeley quarry in 1900, the two quarries were connected underground
Cwt-y-Bugail Slate 1835 1972 1867–1961 Last quarry using the (by then partly lifted) Rhiwbach Tramway
Diphwys Casson Slate 1760 1972 1860–1955 Last of the major quarries to be connected to the Ffestiniog Railway
Graig Ddu Slate 1840 1946  Connected via the Festiniog and Blaenau Railway
Groby Granite Granite 1901 Circa 1932 1914-c.1932 Connected by a short, steeply graded branch worked by FfR locomotives.
Hafodty (Votty) Slate 1801 1870 1851–1870 Joined with Bowydd quarry to form Votty & Bowydd
Llechwedd Slate 1846 Present 1848-1980s Currently worked on a small scale and the site of the Llechwedd Slate Caverns tourist attraction

text: List of quarries served by the Ffestiniog Railway
The quarries
The quarries
Name_ Mineral Opened Closed Years_connected Notes_
Blaen y Cwm Slate 1820 1911 1876–1911 Connected to the FfR via the Rhiwbach Tramway
Bowydd Slate 1800 1870 1854–1870 Merged with Votty to form Votty & Bowydd quarry
Brooke`s Granite 1919 ? ? Connected by a tramway branching off at the north portal of Moelwyn Tunnel
Bwlch-y-Slater Slate 1824 1960 1866–1956 Connected via the Rhiwbach Tramway
Cesail Slate 1827 1877 1836–1877 Became part of the Oakeley Quarry
Conglog Slate 1872 1920? 1874–1920 Remote quarry connected by the Cwmorthin Tramway

text: List of quarries served by the Ffestiniog Railway
The quarries
The quarries
Name_ Mineral Opened Closed Years_connected Notes_
Moelwyn Zinc Zinc, Manganese and Silver c1892 by 1919 1892-by 1919 Zinc mine just west of the north portal of the old Moelwyn Tunnel.
Oakeley Slate 1878 2010 1878-1950s Formed by the amalgamation of the Cesail, Matthews and Glan-y-Pwll quarries. Was the largest single quarry in Blaenau Ffestiniog. Was the home of the Gloddfa Ganol tourist attraction in the 1980s and 1990s. Now worked as an open pit by Alfred McAlpine Ltd.
Rhiwbach Slate 1812 1953 1860–1953 Remote quarry situated 4 miles (6.4 km) east of Duffws station and connected via the Rhiwbach Tramway
Syenite Setts Granite 1874 1916 ? Quarry later worked as Brooke`s
Votty & Bowydd Slate 1870 1964 1870–1962 Formed by the amalgamation of the Hafodty and Bowydd quarries.
Wrysgan Slate 1830s 1946 1844–1946 Connected to the railway near Tanygrisiau via a single long incline ending in a tunnel.

text: List of quarries served by the Ffestiniog Railway
The quarries
The quarries
Name_ Mineral Opened Closed Years_connected Notes_
Maenofferen Slate 1848 1999 1848–1975 Became the major owner of quarries connected via inclines at Duffws station, continued to use the stub of the FfR through Blaenau into the mid 1970s. Untopping operations continue in 2007.
Nyth-y-Gigfran Slate 1840s 1882 1867–1882 Sometimes known as Glan-y-Pwll quarry. Became part of the Oakeley Quarry
Matthews (Rhiwbryfdir) Slate 1825 1871 1842–1871 Became part of the Oakeley quarry
Manod Slate c1850 Present 1866-1930s Sometimes known as Bwlch y Slaters and now given the name Cwt y Bugail. Connected to the Festiniog by the Rhiwbach Tramway
Moelwyn Slate Slate 1826 c 1900 1867–c 1900 Remote quarry connected to the FfR by a series of seven inclines; worked intermittently and never successfully.

Question: From the list of quarries served by the Ffestiniog Railway, how many quarries mined slate?

Question: Of the list of quarries served by the Ffestiniog Railway, at most how many quarries has the Ffestiniog Railway served?