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A mineralogical trip through the regions of the UK - England / Cornwall
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markbeckett




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PostPosted: May 15, 2017 11:43    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Goethite from Wheal Drea, in the Kenidjack Valley, St Just District, Cornwall (also known for its excellent Siderites).


Wheal Drea Goethite.JPG
 Mineral: Goethite
 Locality:
Wheal Drea, Kenidjack Valley, Saint Just, Cornwall, England / United Kingdom
 Dimensions: 9cm x 8cm
 Description:
 Viewed:  10936 Time(s)

Wheal Drea Goethite.JPG


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markbeckett




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PostPosted: May 15, 2017 12:08    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Thought I would post this - for interest's sake more than rarity - Gypsum from Levant Section of Geevor Mine, found growing on the ochreous flooded floor of a stub-drive on Providence Lode, during the final years of the mine. The miners discovered it as it 'crunched' underfoot and lined the whole floor. A post-mining mineral occurrence of note.


Levant Mine Selenite.JPG
 Mineral: Gypsum
 Locality:
Levant Mine, Trewellard, Saint Just District, Cornwall, England / United Kingdom
 Dimensions: 7cm x 4cm
 Description:
Crystals up to 2.5cm.
 Viewed:  10909 Time(s)

Levant Mine Selenite.JPG



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'if you see a strange hill, go and prospect there'...(KFG Hosking)
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markbeckett




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PostPosted: May 16, 2017 11:53    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Also, for interests sake, here is a specimen of Native Silver fine wires and curls from 'Whiteworks', also known as Wheal Maid, United Downs, nr St Day, Cornwall. The bricked-up entrance seals a steel-arched, spiral decline into old mines drained by pumping at Wheal Jane nearby and was once hoped to provide a 'drive-in, drive-out' exit for the then existing Wheal Jane operations. My last visit, years ago, saw the water-table had risen way up the decline, effectively blocking any attempt to re-enter. The killas is highly altered to a white/grey sericitic, sometimes soft consistency, and you come out of the mine 'plastered' with much whiteish clay!
I think this is why it has been known as Whiteworks for so long.

This chance occurrence of Silver there was discovered in a clay-filled 'crosscourse'-type fracture. The 'wires' of the metal were completely admixed with the soft clay, that has now been removed. Mr P. Oldfield of St Just, may well have been the first to discover this - the rest was quickly removed by other collectors. There was also a lot of coarse Cassiterite to be collected at Whiteworks.



Native Silver Whiteworks.JPG
 Mineral: Silver
 Locality:
Wheal Maid, Gwennap, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: 2 or 3 grams
 Description:
 Viewed:  10843 Time(s)

Native Silver Whiteworks.JPG


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PostPosted: May 17, 2017 08:35    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Quartz - Great Perhaver Beach, Gorran Haven (on the Roseland Peninsula), Cornwall

This coastal location is rarely visited by collectors, probably partly due to the fact that the tide has to be quite low to access it. The geological formation that is partially exposed in the back-beach at Perhaver is a part of the 'Roseland Breccia Formation', a mid to late Devonian, thrusted sedimentary 'melange' containing many giant fragments or 'olistoliths (many up to 10 metre size, some smaller, some much larger). Many of the olistoliths are of Ordivician Quartzite and host brittle-fracture quartz veins. These two pieces were part of a find I made there in 1988. These crystals are probably in excess of 400 million years old. They are a part of the oldest sedimentary rocks in Cornwall. The melange (or 'olistostrome') is a member of the 'Gramscatho Group sedimentary rocks.

Cherry-red Sphalerite can also be found in some of the cliff slide material, though appears to be rare there.



Perhaver Beach Gorran Haven.jpg
 Mineral: Quartz
 Locality:
Great Perhaver Beach, Gorran Haven, Saint Austell, Cornwall, England / United Kingdom
 Dimensions: 10cm x 5.5cm
 Description:
 Viewed:  10735 Time(s)

Perhaver Beach Gorran Haven.jpg


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markbeckett




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PostPosted: May 17, 2017 08:38    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Another


Perhaver Beach Quartz2.JPG
 Mineral: Quartz
 Locality:
Great Perhaver Beach, Gorran Haven, Saint Austell, Cornwall, England / United Kingdom
 Dimensions: 6cm x 6cm
 Description:
 Viewed:  10750 Time(s)

Perhaver Beach Quartz2.JPG


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PostPosted: May 17, 2017 09:35    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Datolite with Calcite - Parc Bean Cove, Mullion, Lizard Peninsula, Cornwall.
Datolite in Cornwall is very rare, apart from at the Parc Bean Cove location, that has now been lost, as boulders,to the sea. The matrix is of a highly altered basic igneous rock. This location definitely hosted the best examples in Cornwall.



Mullian Lizard Datolite with Calcite.JPG
 Mineral: Datolite with Calcite
 Locality:
Parc Bean Cove, Mullion, Lizard Peninsula, Cornwall, England / United Kingdom
 Dimensions: 4.5cm x 3cm
 Description:
been magnified a little
 Viewed:  10745 Time(s)

Mullian Lizard Datolite with Calcite.JPG


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PostPosted: May 20, 2017 07:39    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Photos taken underground at South Crofty Mine (Tin) before its closure in the early1990's. This group shows an occurrence of coarsely crystalline Scheelite, associated with Wolframite in Northern Branch lode. After photographing the scene specimens were extracted by careful drilling. Its good to see an actual 'Lode' captured forever in these images - many thanks to P.Oldfield of St.Just, for his kind permission to show these. (hopefully I will get to post a few more soon).


Northern Branch TNL 2.jpg
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Description:
Notice the small 'pods' of dark Wolframite just above the scheelite occurrence
 Viewed:  10530 Time(s)

Northern Branch TNL 2.jpg



Northern Branch TNL 1.jpg
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: scheelite approx 12cm pod, right of centre - lots of wolframite alongside
 Description:
Scheelite is the buff-coloured material
 Viewed:  10542 Time(s)

Northern Branch TNL 1.jpg



Valley Shaft 3.jpg
 Locality:
South Crofty Mine, Valley shaft, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Description:
'Vertigo'!
 Viewed:  10524 Time(s)

Valley Shaft 3.jpg


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markbeckett




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PostPosted: May 20, 2017 13:30    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

(in reference to the above mine shots, 'Northern Branch' TNL' is a piece of Tincroft North Lode - it leaves the main part of the lode just above the 175 fathom level - appearing again in the crosscut to New Cook's Shaft.'). Thanks
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markbeckett




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PostPosted: May 27, 2017 09:26    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

More photos of South Crofty Mine (mainly Tin), Pool,near Redruth, underground. Also taken in the early 1990s by Paul Oldfield -
There were historically over 30 different lode structures that the Mine had access to while in operation. Many of the 'lodes' are a product of 'brecciation versus cataclastic flow' occurring in discreet, fractured zones in the host rock that is either granitic (at depth) or meta-sedimentary (ie. 'in killas') in the shallower parts of the mine. Some of the lodes show more pervasive styles of mineralisation,where wall-rock is also mineralised and can also be associated with meta-basic intrusive rocks, known here as 'greenstones'. Paul's description is transcribed below,

''...in the crosscut north to New Cook's Shaft, Tincroft North Lode was split into three seperate sections, roughly 12metres apart. The footwall contained both arsenopyrite and chalcopyrite with very minor cassiterite and scheelite. As you will see this dips to the north at 45 degrees,whereas the next two are almost vertical. The next section contained sphalerite in bunches with sub-rounded clasts of greenstone wallrock, in quartz. This section was directly above the old ten-fathom level. The last to be encountered before reaching the Northern Branch, was solely chalcopyrite, with side-shoots of fluorite, which here was a bluish-green colour, and was massive. The strange thing was, these on exposure, turned a pale green and lost all of their bluish hue. In one of the photos you see there is a cavity in quartz, or what remains of the quartz. I had to strip the cavity before any further blast damage could occur...''



Tincroft North Lode Footwall.jpg
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: the mine 'drives' are up to many metres in size
 Description:
 Viewed:  10343 Time(s)

Tincroft North Lode Footwall.jpg



Tincroft North Lode with Chalcopyrite.jpg
 Mineral: Chalcopyrite in vein
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: fov is about 2.5metres
 Description:
 Viewed:  10363 Time(s)

Tincroft North Lode with Chalcopyrite.jpg



Tincroft North Lode with Fluorite.jpg
 Mineral: Fluorite
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: fov 20cm
 Description:
 Viewed:  10377 Time(s)

Tincroft North Lode with Fluorite.jpg



Tincroft North Lode with Sphalerite 1.jpg
 Mineral: Sphalerite
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: fov 2m
 Description:
 Viewed:  10378 Time(s)

Tincroft North Lode with Sphalerite 1.jpg



Tincroft North Lode with Sphalerite 2.jpg
 Mineral: Sphalerite
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: fov approx. 1metre
 Description:
 Viewed:  10361 Time(s)

Tincroft North Lode with Sphalerite 2.jpg


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markbeckett




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PostPosted: May 27, 2017 10:07    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Another South Crofty Mine photo, of an 'end' (of tunnel) that exposes a flat-laying 'magmatic sill' of granitic composition, (in the floor of the drive), that is intruded into the dark 'killas' around it. Flow-banding was recognised in its bulk texture. It occurred with tendril-like extensions or 'droppers' of finer-grained 'aplite' rock. The white spray painted lines were in preparation for the next blast. Photo by Paul Oldfield.


Granite Sill when it first appeared.jpg
 Mineral: Granitic sill.
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: 3 or 4 metres
 Description:
Other flat-lying magmatic structures at South Crofty are known as 'quartz floors' and were coarsely crystalline, with feldspar, wolframite and cassiterite.
 Viewed:  10357 Time(s)

Granite Sill when it first appeared.jpg


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markbeckett




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PostPosted: Jun 09, 2017 08:59    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Here are some attractive specimens from Penlee Quarry, near Mousehole, Cornwall. The quarry has been worked for roadstone in the past but plays host to a complex exposure of metamorphosed 'greenstone' (metabasic intrusive), with some granite, associated with some highly altered 'killas' (meta-pelite). Mineralisation includes arsenopyrite, lollingite, pyrites, chalcopyrite, bismuth, topaz, molybdenite, chalcedony, siderite and scheelite with some wolframite and cassiterite with chlorite.
The following photos are of Chalcedony and Siderite, retrieved from a 'crosscourse' (ie. a vein emplaced in a different orientation to most other fractures). The last two pics are of the manual 'development' of the exposed crosscourse, from 'discovery to extraction' with hand tools.



Chalcedony + Siderite X-Course 1.JPG
 Mineral: Siderite on Quartz (variety chalcedony)
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: 6x5 cm
 Description:
Photo by P. Oldfield
 Viewed:  10187 Time(s)

Chalcedony + Siderite X-Course 1.JPG



Chalcedony + Siderite X-Course.JPG
 Mineral: Siderite on Quartz (variety chalcedony)
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: 6x5 cm
 Description:
Photo by P. Oldfield
 Viewed:  10222 Time(s)

Chalcedony + Siderite X-Course.JPG



Chalcedony Red X-Course.JPG
 Mineral: Quartz (variety chalcedony)
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: about hand-size
 Description:
Photo by P. Oldifield
 Viewed:  10210 Time(s)

Chalcedony Red X-Course.JPG



Chalcedony X-Course 1.jpg
 Mineral: Quartz (variety chalcedony)
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Description:
Photo by P. Oldfield
 Viewed:  10216 Time(s)

Chalcedony X-Course 1.jpg



Chalcedony Yellow X-Course.JPG
 Mineral: Quartz (variety chalcedony)
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: 6x4.5cm
 Description:
Photo by P. Oldfield
 Viewed:  10179 Time(s)

Chalcedony Yellow X-Course.JPG



Penlee X-course February 2002.jpg
 Mineral: A 'crosscourse' vein
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: a few metres width
 Description:
photo by P. Oldfield, taken before an attempt to 'open it up'.
 Viewed:  10189 Time(s)

Penlee X-course February 2002.jpg



Penlee X-course May 2002.jpg
 Mineral: A 'crosscourse' vein
 Locality:
Penlee Quarry, Mousehole, Penzance Civil Parish, Cornwall, England / United Kingdom
 Dimensions: a few metres
 Description:
Photo by P. Oldfield - this was taken after initial development with hand-tools, a couple of months later.
 Viewed:  10174 Time(s)

Penlee X-course May 2002.jpg


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markbeckett




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PostPosted: Jun 11, 2017 08:55    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

This is a specimen that was retrieved from the ochreous/iron oxide filled 'pocket' within the South Crofty 'Tincroft North Lode', indicated in my earlier posting (I have repeated that photo as I thought it should be linked again here).


Tincroft North Lode with Sphalerite 1.jpg
 Mineral: Quartz
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: a couple of metres
 Description:
Check out the quartzy, ochreous pocket that was extracted just after the ealier blast, about centre-right in the image.
 Viewed:  10084 Time(s)

Tincroft North Lode with Sphalerite 1.jpg



Quartz-Pyrite Tincroft North 1.JPG
 Mineral: Quartz with Pyrite
 Locality:
South Crofty Mine, Northern Branch lode, Pool, Camborne - Redruth - Saint Day District, Cornwall, England / United Kingdom
 Dimensions: about 11cm max size
 Description:
Photo by P. Oldfield, from his collection.
 Viewed:  10084 Time(s)

Quartz-Pyrite Tincroft North 1.JPG


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Colin Fearon




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PostPosted: Oct 30, 2020 08:28    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Hi Ian, I was just doing some on-line surfing when I came across your pic of the Botallack copper from the William's Collection.

I have a similar copper from Botallack which I purchased from Paul Lowe in Truro sometime in the nineties. Also from the Williams Collection but also with the number 112 affixed to it!. One of a pair or just a mis-numbering?

Regards
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ian jones




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PostPosted: Oct 30, 2020 08:52    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

That's interesting Colin. Will check the number of mine next time I manage to get home, probably in a couple of weeks, just in case it's incorrect.

Otherwise, I have no idea whether Col William's ever gave similar pairs of specimens the same number, but certainly not to my knowledge.

ian
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James Catmur
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PostPosted: Oct 30, 2020 08:57    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

I assume we are talking about this specimen

https://www.mineral-forum.com/message-board/viewtopic.php?p=34455#34455

James
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Colin Fearon




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PostPosted: Oct 30, 2020 09:26    Post subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall  

Hi James, yes we are. My specimen is slightly larger at 6" x 4" (150mm x 100mm)
and with much finer wires
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