Hunt the elvans

Before this series of post’s about the geological map of the Liskeard area launches into the ‘main event’, of the lodes it will have a pause at feature with the best sounding name, Elvan.

Elvans are intrusions of a quartz porphyry rock; the word is used for both the intrusion and the rock itself. Elvan is a very hard rock that can add greatly to the cost of driving levels and sinking shafts. Elvan patches near lodes were also thought to be associated with increased mineral richness. Its hardness made it a sought after building material.

Brenton Symons in his 1863 map shows elvans as red colour washed areas. He has shown eight setts in Caradon Hill area with elvan patches, as opposed to the British Gelogical Survey’s moderm map not indicating any.

No Elvan patches are shown at all by BGS.

“There  are  also  several  strong  elvans  or  dykes  generally  running  about  parallel  with  the lodes,  and  which  so  far  as  seen,  have  had  a  beneficial  effect.”

Webb and Geach

West Sharp Tor

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There  is  a  very  large  elvan  course,  north  of,  and  adjoining  the  lode;  the  thickness  of  which  though  driven  into  6  fathoms,  is  not  yet  known.

East Phoenix

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There  is  a  beautiful  white  elvan,  50  fathoms  east  of  the engine  shaft,  about  3  fathoms  wide.

Wheal Pollard

At  the  11 an  elvan  course  came  in  and  heaved  the  lode  south.

The  elvan,  of  which there  are  two  channels,  is  harder  than  general  in  the  district.”

Wheal Norris

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Caradon Consols

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East Wheal Agar

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“There  is  a  beautiful  white regular  elvan  course  70  fathoms  south  of  the  shaft,  whilst  the  Junction  of killas  and  granite  occurs  between  it  and  Dunsford’s  Shaft”

East Caradon

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“There  is  a  large  elvan  course  north  of and  accompanying  the  caunter,  and  in  the  same  elvan  a  little  north,  occurs Fawcett’s  Lode,  which  has  been  opened  on  for  some  distance:”

Wheal Caradon
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“There  are two  elvan  courses;  one  occupying  the  whole  space  between  the  north  and middle  lodes,  and  the  other  in  the  south  portion  of  the  sett;  white  porphyritic dykes almost destitute of mica, composed chiefly of feldspar and quartz.”

Wheal Hooper
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“It should be  noticed  that  two  elvan  courses  of  felspatic granite run parallel to the lodes.”

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