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Quarrying Techniques - Working the Slate

the workers the quarry and blasting
working the slate mechanisation

A quarryman splitting slates(It is very important to bear in mind that since the quarrying was a Welsh language industry, the translations into English are only meant to give an idea of the meaning of the original. These English versions are modern literal translations. It is important to know that the terminology did vary to some extent from area to area. The terms used here are in the main from the Llanberis area.)


The bargen is assessed before seeing to the llnau (cleaning up) as well as ascertaining that there is no dangerous crib yn hongian (overhang) remaining. Then it was time to dragio, (lit dragging), that is to use a cyn manhollt (lit. small splitting chisel) and the morthwyl dragio (a three pound hammer) to brashollti’r plygion (rough slit the slate blocks) with the grain, into pileri (pillars) between 30 and 60 cms wide. These would then be lifted on to the sledge, but using a crane today of course to be transported to the wal (shed.) This, before the siediau hollti, (chipping sheds) were built during the second half of the twentieth century, was an area around 90cm to105cm where the holltwr (splitter) and naddwr (chipper) would work. There is a circular saw, (diamond by today) in the shed to saw the clytiau (small blocks) into crawiau tenau (thin slabs) ready to be split. Once split, the slate then becomes y garreg, (lit. the stone.)

Hollti (splitting) needs a very special expertise. The holltwr sits on a block of wood known as the blocyn hollti (splitting block) or blocyn tin (bum block), legs folded, with the clwt resting on his left knee. His tools are two or three-cyn manollt or a cyn tew wyth (lit. a chisel fat eight, [fat eight meaning a block of slate wide enough to be split into eight slates,]) together with a gordd y wal (a wooden mallet of African oak.) The thickness of the best stones are six stones to 2cm. The crawiau are then placed on a flat stone, the garreg bentwr (pile slab) ready to be chipped. The jermon is usually responsible for this.

Then the naddwr places the crawen dena or sglodyn (chips) on the blade of the drafael (a bench with a fixed iron blade, used in conjunction with the cyllell naddu [lit. chipping knife] for hand trimming roof slate.) A machine is used for this process by now. Two sides are cut straight first to achieve a straight edge. It is then measured using the pren mesur lit. a measuring stick.) This is a piece of wood, a nail at one end with graduated inch steps till fourteen inches is reached, the changing to two inch steps until twenty four inches is reached. After marking the slate, two remaining sides are then chipped resulting in a perfect rectangular slate of the proper dimensions. Before the days of the engine, an experienced chipper could reach a target of between five hundred and six hundred finished roof slates a day.

Electrically driven machines are now used. Granted finished slates are produced much quicker, but more waste is produced especially if the slates are exceptionally thick or hard.

Llanberis quarrying terms were used here, but it must also be remembered that there were variations of names used in different localities.

In Blaenau Ffestiniog a vein of slate was known as a llygad - llygadau (eye-eyes). It was a name given since the quarrymen would open the rock, thus opening the slate's 'eye.'

Llygadau Names of Blaenau Ffestiniog

Llygad Mochyn
Llygad Cefn/Llygad Coch (back/red) 
Llygad Bach (little) 
Hen Lygad
Llygad Newydd 
Llygad y Moelwyn 
Llygad Thomas Edwards 
Llygad Glan y Pwll 
Llygad Llwyd 
North Vein
Back Vein
Narrow vein
Old Vein
Lygad y Graig Ddu (black rock eye)
Moewlyn Vein
Second Moelwyn Vein
Olive Vein
Grey Vein

Gwythien (Vein) is a thin layer of rock, many of which are found in a gwely (bed). The width of the Hen Lygad in one of the Ffestiniog Quarries is 70 yards and contains 27 veins.

Widths and Veins of the Hen Lygad

Ithfaen glas (slont glai) 
Gwythien y Meinars 
Y Wythien Isaf a'r Tri Teulu 
Gwythien Crych Du Bach 
Gwythien Crych Du Mawr 
Y Wythien Sylffar 
Y Pum Wythien 
Y Wythien rhwng y Pump a'r Wythien Wen 
Y Wythien Wen a'r Teulu 
Yr Ail oddi-wrth y Wythien fawr 
Y Wythien Fawr 
Y Wythien Ddu 
Y Wythien Gam 
Yr Ail Wythien Gam 
Y Gwythiennau Mân..y gorn a'r frith 

Pen Uchaf y Llygad Caled (tew bras) 
Y Wythien Galed a'r Teulu 
Yr Ail Wythien Galed 
Y Wythien Lwyd 
Y Wythied Fflat 
Y Wythien Grych 
Sylffar y Llygad Caled Isaf 
Y Wythien Galed Isaf 
Gwythien y Smotiau Isaf 
Gwythien y Sylffar Du a'r rhai diweddaf 
blue granite
miners' vein
lower vein and three family
small black crooked vein
great black crooked vein
the sulphur vein
the five vein
the vein between the five and the 
white vein
the white vein and family
the second from the great vein
the great vein
the black vein
the crooked vein
the second crooked vein
the small veins..the horned and 
top head of the hard eye 
the hard vein and family
the second hard vein
the grey vein
the flat vein
the crooked vein
the sulphurous hard lower eye
the lowest hard vein
the lower spotted vein
the black sulpgur vein and the 
latest ones

This is the traditional way Slates were Counted:

Cant bach 

Cant mawr 
Dau gant bach 
3 carreg (slates)
10 mwrw and 2 garreg (32 slates)
4 cant bach (128 slates)
1 pwn ceffyl (horse pack)

Slate sizes

It is believed that it was Colonel Hugh Wilburton of Winnington, Cheshire, and co owner of the Penrhyn estate who invented the names of some at least of the various slate sizes. As Chancellor and Chamberlain of Anglesey, Caernarfon shire and Meirionydd he was very influential figure. Indeed he was appointed as first Provincial Grand Master of the Masonic Province of North Wales, holding the post until 1741, when William Vaughan of Corsygedol was appointed in his stead, who was one of the founder members of the London Cymmrodorion Society and a great friend of the Morris brothers. His only child and heiress, Ann, married Richard Pennant, the first Lord Penrhyn of the first creation in 1765. Their marble memorial can be seen in the parish church of Llandygai.These are the names and sizes of the various roof slates in inches.

Queens 24x40
Empresses 26x16
Princesses 24x14
Duchesses Mawr (Large) 24x12
Duchesses Bach (Small) 22x12
Duchesses Cul (Narrow) 22x11
Countesses Mawr 20x12
Countesses Deg (Ten)  20x10
Countesses Bach 18x12 a 10x9
Ladis (Ladies) 16x12
Ladis Llydan 16x10 and 16x9
Ladis Dwbl Dwbl Cul (narrow) 16x8 and 14x10
Ladis Bach 14x12 and 14x8
Ladis Dwbl Cul 12x6
Ladis Single  12x4.5
Ladis Single 10x5
Dampcourse (naw pedair a hanner) 9x4½

The slates were counted every 1,000, i.e. 1,260.

At the end of the day the slates were carried out and piled tidily in the clwt peilio (stacking plot.) They were then classified not only according to their sizes but also according to their thickness. All these stones were then given up at the end of every mis chwarel, (quarry month) which was exactly four weeks. Slates were counted in three (mwrw.)

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