Geology Cornwall

Background picture Granite from St.Stythyans Parish.

 

 

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Event Reports

Suitable equipment must be worn at all times in quarries such as Greystones quarry.

 

 

TREWAVAS FIELD TRIP 2011(RGSC)

LEADER STEPHEN POLGLASE

 

The day was a very pleasant sunny Sunday.  About15 people set off along the coastal footpath from Rinsey Car Park.   It was a very easy walk that took us past the mine dumps marked by three cairns that had been built by some unknown persons.   Continuing along the path we eventually caught sight of the two engine houses and horse whim spectacularly situated halfway down from the sheer cliff top and about 100 ft above the sea.   Because of the steepness of the cliffs a tramway was built to bring coal down and take ore up using the horse whim.   The engine houses had recently been refurbished by the National Trust.    One engine house has a very large opening through which the steam engine would have been taken for installation.  It is believed that the original 45” engine was replaced with a much larger ?85” engine.   Due to the terrain it must have  been quite an achievement to have managed to successfully install it.

There was a rich copper lode that went out under the sea.  At the 45 fathom level the lode was 3ft wide with the richest mineralisaton 2ft wide.  The mine finally reached a depth of 85 fathoms but it is believed the sea finally broke in and flooded it, the lode at the 45 fathom level being very close to the sea bed.

Having examined both engine houses the party returned trying to conjecture when the leat must have run to feed the engines.   A very pleasant day enjoyed by all.

 

 

WILLIAMS COLLECTION 2011(RGSC)

A TALK BY COURTENEY SMALE

Courteney Smale gave a talk on the work he was asked to carry out on the Williams Collecton at Caerhayes Castle.  He began by explaining that the retired County Records Officer, Christine North, had introduced him to the problem.

 

It appeared that after the 1880s the family had taken no interest in the collection and it had been stored and ignored for many years.   Courteney was presented with two cabinets of micromounts which he began to catalogue.   It is believed that the cabinets and minerals were previously supplied as a package by a well known mineral supplier of the time.

 

He then began to receive phone calls that more rocks had been found.  Eventually minerals were being found all over the house – the kitchen, the wine cellar, the vegetable store and there are possibly still other boxes to be found.

 

Having unpacked the boxes many of the sulphide material had to be disposed of as it had been badly affected by the damp and disintegrated.   However, some of the other minerals only needed washing in warm water to display their beauty.

 

Many of the examples possessed large crystals:  a wonderful selection of Chessy, France azurites; large torbernite crystals from Gunnislake, beautiful Australian opals and many Wheal Gorland minerals such as liroconite, clinoclase and olivenite.

 

Courteney asked whether there was any index in existence that he could use to begin the identification process.   None could be found until towards the end of his efforts, a box with a list in it was located.   This meant that he had to review each of the minerals in order to establish that he had correctly identified them in the first place!

 

Very unfortunately it did not prove possible to show the photographs that had been intended to illustrate this talk.   However, it was agreed that at a future date this talk would be repeated to include these.

 

 

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