Table:
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
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
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.
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.

Question: which quarry was the last to open?
Answer: Brooke's

Question: looking at the top of the table, what is the name of the first quarry listed, and what year did it close?
Answer: Blaen y Cwm|1911

Question: how many quarries was slate mined at?
Answer: 20

Question: the ffestiniog railway serviced at most how many slate quarries?
Answer: 20

Question: how many quarries opened before 1892?
Answer: 22

Question: what is the last operating quarry that connects to the rhiwbach tramway?
Answer: Cwt-y-Bugail

Question: how many years was the cesail mine connected?
Answer: 41