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The slate industry is the industry related to the extraction and processing of slate. For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious" Slate is a fine-grained foliated homogeneous, Metamorphic rock derived from an original Shale -type Sedimentary rock composed of Clay Slate is either quarried from a slate quarry or reached by tunneling in a slate mine. Open-pit mining, also known as opencast mining and open-cut mining and strip mining, refers to a method of extracting rock or Minerals Common uses for slate include as a roofing material, a flooring material and for electrical insulation. Slate mines are found around the world and major slate mining regions include Wales, Cornwall (famously the town of Delabole) and the Honister slate mine in the Lake District in the United Kingdom, Portugal, Fumay in the Ardennes, the east coast of Newfoundland, and the Slate Valley of Vermont and New York. Cornwall ( Kernow ˈkɛɹnɔʊ is the most southwesterly county of England, on the Peninsula that lies to the west of the River Tamar Delabole is a village in North Cornwall, England. It is the third highest village in Cornwall the two highest are also in the North Cornwall district The Lake District, also known as The Lakes or Lakeland, is a rural area in North West England. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula. Fumay is a commune in the Ardennes department in northern France, very close to the Belgian border For the political subdivision of France see Ardennes (department. Newfoundland — ˈn(jufənˌlænd (Terre-Neuve Talamh an Éisc — is a large island 15 km off the east coast of Vermont ( is a state in the New England region of the northeastern United States of America. New York ( is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous This area, centering on a town called Granville NY is the only place in the world where colored slate is mined.

Contents

Slate industry in Wales

Background

main article Slate industry in Wales
Bridge over a chamber
Bridge over a chamber

Slate has been mined in north Wales for several centuries — this was recently confirmed by the discovery in the Menai Strait of the wreck of a 16th century wooden ship carrying finished slates. The slate industry in Wales began during the Roman period when Slate was used to Roof the fort at Segontium, now Caernarfon. The Menai Strait ( Afon Menai, the "River Menai" is a narrow stretch of shallow tidal water about 14 miles (23 km long which separates the island of Anglesey

Large-scale commercial slate mining in North Wales began with the opening of the Cae Braich y Cafn quarry, later to become the Penrhyn Quarry near Bethesda in the Ogwen Valley in 1782. The slate industry in Wales began during the Roman period when Slate was used to Roof the fort at Segontium, now Caernarfon. The Penrhyn Slate Quarry is a Slate Quarry located near Bethesda in north Wales. Bethesda is a Town lying on the River Ogwen and the A5 road on the edge of Snowdonia, in Gwynedd, north-west Wales, Welsh output was far ahead of other areas and by 1882, 92% of Britain's production was from Wales (451,000t): the quarries at Penrhyn and Dinorwic Quarry produced half of this between them.

The men worked the slate in partnerships of four, six or eight and these were known as "Bargain Gangs". "Bargains" were let by the "Bargain Letter" when a price for a certain area of rock was agreed. Adjustments were made according to the quality of the slate and the proportion of 'bad' rock. The first Monday of every month was "Bargain Letting Day" when these agreements were made between men and management. Half the partners worked the quarry face and the others were in the dressing sheds producing the finished slates. In the Glyndyfrdwy mines at Moel Fferna each bargain worked a horizontal stretch of 10 by 15 yards. Duchesses, Marchionesses, countesses, Viscountesses, Ladies and Small Ladies, Doubles and Randoms were all sizes of slates produced.

Rubblers helped to keep the chambers free from waste: one ton of saleable slate could produce up to 30 tons of waste. It is the mountainous heaps of this very same waste that is perhaps the first thing to strike someone visiting the old regions nowadays. The men had to pay for their ropes and chains, for tools and for services such as sharpening and repairing. Subs (advances) were paid every week, everything being settled up on the "Day of the Big Pay". If conditions had not been good, the men could end up owing the management money. At Moel Fferna a team could produce up to 35 tons of finished slate a week. In 1877 they received about 7 shillings a ton for this. After paying wages for the manager, clerks and 'trammers' the company could make a clear profit of twice this amount. This system was not finally abolished until after the Second World War.

Working methods

Early workings tended to be in surface pits, but as the work progressed downwards, it became necessary to work underground. This was often accompanied by the driving of one or more adits to gain direct access to a Level. In some rare instances, such as Moel Fferna, there is no trace of surface workings and the workings were entiely underground.

Chambers were usually driven from the bottom, by means of a "roofing shaft" which was then continued across the width of the chamber: the chamber would then be worked downwards. Slate was freed from the rockface by blasting in shot holes hammered (and later drilled) into the rock.

Slate would be recovered from the chamber in the form of a large slab, which would be taken by truck to the mill where it would be split and cut into standard-sized roofing slates.

Slate mines were usually worked in chambers which followed the slate vein, connected via a series of horizontal "Floors" (or "Levels"). The chambers varied in size between mines and were divided by "pillars" or walls which supported the roof. The floors were connected by underground "Inclines" which used wedge-shaped trolleys to move trucks between levels.

In some mines, where slate was worked away below the main haulage floor, the route was maintained through the construction of a wooden bridge across the chamber, often supported from chains attached to the roof above. These bridges could be as much as 100 feet/30 m above the floor below.

Significant mines

In North Gwynedd, the large slate producing quarries were usually confined to open-cast workings, sometimes with an adit to gain access to the bottom of the pit:

In the Blaenau Ffestiniog area, most of the workings were underground as the slate veins are steeply angled and open cast workings would require the removal of a massive amount of rock to gain access to the slate. Blaenau Ffestiniog is a small Town in Gwynedd, north-west Wales. The larger mines in the Ffestiniog area include:

Chamber in a slate mine
Chamber in a slate mine

There were also a number of slate mines in the Llangollen area which produced a much darker "black" slate:

Another cluster of mines were found in mid Wales centered on Corris. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Maenofferen Quarry is a major slate quarry in the town of Blaenau Ffestiniog, north Wales and one of the major users of the Ffestiniog Railway The Croesor Tramway was a Welsh Narrow gauge railway line built to carry Slate from the Croesor slate mines to Porthmadog. Llangollen (ɬaŋ'ɡoɬɛn is a small town in Denbighshire, north-east Wales, situated on the River Dee and on the edge of the Berwyn King George's Fields SH7507 195jpg|240px|right|thumb|The entrance to King George's Field next door to the junior school]] Corris is a Village in the south of These all worked a pair of slate veins that ran across the Cambrian mountain range from Bryn Eglwys in the west through Corris and Aberllefenni in the Dulas Valley to the mines around Dinas Mawddwy in the east. Bryn Eglwys was a remote slate Quarry located near Abergynolwyn in Gwynedd mid- Wales. Aberllefenni is a Village in the south of Gwynedd, Wales. It lies in the valley of the Afon Dulas. Dinas Mawddwy is a Village in Gwynedd, North Wales, just to the side of the A470 so that most visitors pass the village by

Remains

Remains of a bridge in a flooded chamber
Remains of a bridge in a flooded chamber

Most underground slate mines in north Wales were closed by the 1960s although some open-cast quarries have remained open, including the Penrhyn Quarry and the untopping work at Oakeley in Blaenau Ffestiniog. Blaenau Ffestiniog is a small Town in Gwynedd, north-west Wales. Work also continues at Berwyn near Llangollen. The final large-scale underground working to close was Maenofferen Quarry (which is owned by the Llechwedd tourist mine) in 1999 although opencast quarrying continues at this location. Maenofferen Quarry is a major slate quarry in the town of Blaenau Ffestiniog, north Wales and one of the major users of the Ffestiniog Railway

Many of the mines are now in a state of considerable decay and those that are accessible should not be entered as they are on private property and contain many hidden dangers. The lower levels of many mines are now flooded and collapses are commonplace, for example the hillside above the Rhosydd workings has many pits where the roofs of the chambers below have collapsed.

Slate industry in the Lake District

During the last 500 years, much slate extraction has taken place the Lake District at both surface quarries and underground mines. The major workings are:

Slate industry in North America

Slate quarry at Monson, Maine
Slate quarry at Monson, Maine

The slate industry in the United States is concentrated in the Taconic Mountains region of Vermont and New York, known as the Slate Valley. Monson is a town in Piscataquis County, Maine, United States. The State of Maine ( is a state in the New England region of the northeastern United States of America, bordering the Atlantic Ocean The United States of America —commonly referred to as the Vermont ( is a state in the New England region of the northeastern United States of America. New York ( is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous Slate was first quarried in 1839 at Fair Haven, Vermont. Fair Haven is a town in Rutland County, Vermont, United States. An influx of immigrants from the North Wales slate quarrying communities saw a boom in slate production that peaked between the late 1850s and early 1900's. The slate of the region comes in a variety of colors, notably green, gray, black and red. Some production continued in 2003 with 23 operating full-time mines employing 348 people [1].

Large scale slate quarrying also took place around the town of Monson, Maine where an extensive series of quarries flourished from the 1860s onwards. Monson is a town in Piscataquis County, Maine, United States. The State of Maine ( is a state in the New England region of the northeastern United States of America, bordering the Atlantic Ocean A small scale quarrying and dressing operation continues in Monson into the 21st. century.

Notes

  1. ^ Lindsay p. 314

See also

Further reading

External links

British industrial narrow gauge railways are narrow gauge Railways in the United Kingdom and the Isle of Man that were primarily built to serve Mine Exploration is a Hobby in which people visit Abandoned mines and quarries (and sometimes working mines) to
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