Finding your own semiconductors - Revision history

Cornish semiconductor at 12:49, 27 June 2026

2026-06-27T12:49:22Z

← Older revision		Revision as of 12:49, 27 June 2026
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	I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.		I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.

			==Some documented field trips==

			As part of the [[ACE R&D project\|Arts Council England R&D project]] I am documenting some trips to search for natural semiconductors in abandoned mine sites around Cornwall:

			* [[Porthtowan/Nangiles exotic semiconductor field trip]]

Cornish semiconductor: /* Safety */

2026-06-26T16:38:58Z

Safety

← Older revision		Revision as of 16:38, 26 June 2026
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	Use a proper rock hammer to split rocks - normal hammers can splinter dangerously if they are not designed for the purpose. Use eye protection and gloves (all the time), it's quite common for flakes of rock to shoot out at high velocity when hammering (making a sound like a ricocheting bullet in an old film), and the sharp edges of freshly broken quartz can easily cut hands.		Use a proper rock hammer to split rocks - normal hammers can splinter dangerously if they are not designed for the purpose. Use eye protection and gloves (all the time), it's quite common for flakes of rock to shoot out at high velocity when hammering (making a sound like a ricocheting bullet in an old film), and the sharp edges of freshly broken quartz can easily cut hands.

	Arsenic and lead are toxic, and are contained in a lot of the minerals and rocks in the area. While in the mineralised forms we handle them in they are not massively dangerous - always wash your hands after handling any minerals. If grinding or working dry material wear a good face mask, or use water to avoid any entering your lungs.		Arsenic and lead are toxic, and are contained in a lot of the minerals and rocks in the area. While in the mineralised forms we handle them in they are not massively dangerous - always wash your hands after handling any minerals. If grinding or working dry material wear a good face mask, and use water to avoid any entering your lungs.

	Only go to sites that are on public land - not only for aspects of legality (collecting on private land can be permitted, but it's a more complex situation) but also because these areas are more likely to have their mine shafts well indicated and made safe. Never enter mine workings or old buildings. Often the riskiest aspect of these sites are the mountain bikers we share them with - but we like them because they turn over the ground and expose new rocks!		Only go to sites that are on public land - not only for aspects of legality (collecting on private land can be permitted sometimes, but it's a more complex situation) but also because these areas are more likely to have their mine shafts well indicated and made safe. Never enter mine workings or old buildings. Often the riskiest aspect of these sites are the mountain bikers we share them with - but we like them because they turn over the ground and expose new rocks!

	I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.		I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.

Cornish semiconductor at 14:49, 26 June 2026

2026-06-26T14:49:22Z

← Older revision		Revision as of 14:49, 26 June 2026
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			[[Category: ACE R&D]]
	[[File:Cut-s.jpg\|500px\|right]]		[[File:Cut-s.jpg\|500px\|right]]

Cornish semiconductor: /* What to look for */

2026-06-21T15:51:03Z

What to look for

← Older revision		Revision as of 15:51, 21 June 2026
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	Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].		Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].

	See also the full [[list of ~~semiconducting~~ minerals]].		See also the full [[list of minerals tested]].

	It's worth mentioning that while quartz has its own particular place in electronics history (not least in the extraction of silicon) it is not a semiconductor, and not useful for our purposes here.		It's worth mentioning that while quartz has its own particular place in electronics history (not least in the extraction of silicon) it is not a semiconductor, and not useful for our purposes here.

Cornish semiconductor: /* What to look for */

2026-06-21T15:50:40Z

What to look for

← Older revision		Revision as of 15:50, 21 June 2026
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	Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].		Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].

			See also the full [[list of semiconducting minerals]].

	It's worth mentioning that while quartz has its own particular place in electronics history (not least in the extraction of silicon) it is not a semiconductor, and not useful for our purposes here.		It's worth mentioning that while quartz has its own particular place in electronics history (not least in the extraction of silicon) it is not a semiconductor, and not useful for our purposes here.

Cornish semiconductor: /* Safety */

2026-06-21T15:48:57Z

Safety

← Older revision		Revision as of 15:48, 21 June 2026
Line 29:		Line 29:
	Use a proper rock hammer to split rocks - normal hammers can splinter dangerously if they are not designed for the purpose. Use eye protection and gloves (all the time), it's quite common for flakes of rock to shoot out at high velocity when hammering (making a sound like a ricocheting bullet in an old film), and the sharp edges of freshly broken quartz can easily cut hands.		Use a proper rock hammer to split rocks - normal hammers can splinter dangerously if they are not designed for the purpose. Use eye protection and gloves (all the time), it's quite common for flakes of rock to shoot out at high velocity when hammering (making a sound like a ricocheting bullet in an old film), and the sharp edges of freshly broken quartz can easily cut hands.

	Arsenic and lead are toxic, and are contained in a lot of the minerals and rocks in the area. While in the mineralised forms we handle them in they are not massively dangerous - always wash your hands after handling any minerals.		Arsenic and lead are toxic, and are contained in a lot of the minerals and rocks in the area. While in the mineralised forms we handle them in they are not massively dangerous - always wash your hands after handling any minerals. If grinding or working dry material wear a good face mask, or use water to avoid any entering your lungs.

	Only go to sites that are on public land - not only for aspects of legality (collecting on private land can be permitted, but it's a more complex situation) but also because these areas are more likely to have their mine shafts well indicated and made safe. Never enter mine workings or old buildings. Often the riskiest aspect of these sites are the mountain bikers we share them with - but we like them because they turn over the ground and expose new rocks!		Only go to sites that are on public land - not only for aspects of legality (collecting on private land can be permitted, but it's a more complex situation) but also because these areas are more likely to have their mine shafts well indicated and made safe. Never enter mine workings or old buildings. Often the riskiest aspect of these sites are the mountain bikers we share them with - but we like them because they turn over the ground and expose new rocks!

	I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.		I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.

Cornish semiconductor: /* Safety */

2026-06-21T15:46:49Z

Safety

← Older revision		Revision as of 15:46, 21 June 2026
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	==Safety==		==Safety==

			Use a proper rock hammer to split rocks - normal hammers can splinter dangerously if they are not designed for the purpose. Use eye protection and gloves (all the time), it's quite common for flakes of rock to shoot out at high velocity when hammering (making a sound like a ricocheting bullet in an old film), and the sharp edges of freshly broken quartz can easily cut hands.

			Arsenic and lead are toxic, and are contained in a lot of the minerals and rocks in the area. While in the mineralised forms we handle them in they are not massively dangerous - always wash your hands after handling any minerals.

			Only go to sites that are on public land - not only for aspects of legality (collecting on private land can be permitted, but it's a more complex situation) but also because these areas are more likely to have their mine shafts well indicated and made safe. Never enter mine workings or old buildings. Often the riskiest aspect of these sites are the mountain bikers we share them with - but we like them because they turn over the ground and expose new rocks!

			I take a Geiger counter with me so I can tell if I'm near radioactive rocks. It's rare that this happens, but in some mines the background radiation is noticeably higher, if not at dangerous levels in itself. Uranium ores can be found (very rare and quite valuable) so it's good to know if you need to treat them carefully - or more safely leave them where they are.

Cornish semiconductor: /* What to look for */

2026-06-21T15:35:05Z

What to look for

← Older revision		Revision as of 15:35, 21 June 2026
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	Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla. These are very colourful but not useful for our purposes, however some of these secondary forms, such as [[chalcocite]] (or grey copper) and [[cuprite]] are also great semiconductors themselves.		Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla. These are very colourful but not useful for our purposes, however some of these secondary forms, such as [[chalcocite]] (or grey copper) and [[cuprite]] are also great semiconductors themselves.

			The other material that Cornwall has become associated with is tin, which was mined for centuries before copper became important. The principle ore of tin is [[cassiterite]] which can also be found in the waste dumps. It is extremely heavy (six times the mass of water) and is also a semiconductor.

	Another element that is very common is arsenic, which binds with sulphur to form [[arsenopyrite]] or more rarely oxygen to form [[löllingite]]. These are both great semiconductors.		Another element that is very common is arsenic, which binds with sulphur to form [[arsenopyrite]] or more rarely oxygen to form [[löllingite]]. These are both great semiconductors.

	~~The other material that Cornwall has become associated with~~ is ~~tin~~, ~~which was mined for centuries before copper became important. The principle ore~~ of ~~tin is~~ [[~~cassiterite~~]] ~~which can also be~~ found in ~~the waste dumps. It~~ is ~~extremely heavy (six times the mass of water)~~ and ~~is also~~ a ~~semiconductor~~.		Lead is fairly common also, in the form of [[galena]] and it's many secondaries. Galena is often found in small patches and veins, material that is courser and richer that can be separated to use with a cat's whisker can be more tricky to find.

	Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].		Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].

Cornish semiconductor: /* What to look for */

2026-06-21T15:26:20Z

What to look for

← Older revision		Revision as of 15:26, 21 June 2026
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	==What to look for==		==What to look for==

	Most often in the case of searching for semiconductors, we are looking for metallic mineralisation - the most abundant metal is iron, which is often associated with rarer metals. We are looking for heavy, red or yellow iron stained rocks - often coated in goethite, which is one of the minerals that comprises rust.		Most often in the case of searching for semiconductors, we are looking for metallic mineralisation - the most abundant metal is iron, which is often associated with rarer metals. We are looking for heavy, red or yellow iron stained rocks - often coated in goethite, which is one of the minerals that comprises rust. Usually the most common metallic shiny mineral you'll find is [[pyrite]] or fool's gold, this is a semiconductor - particularly the badly decayed and not well crystallised forms of it.

	Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla, some of these secondary forms, such as [[chalcocite]] (or grey copper) and [[cuprite]] are also great semiconductors themselves.		Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla. These are very colourful but not useful for our purposes, however some of these secondary forms, such as [[chalcocite]] (or grey copper) and [[cuprite]] are also great semiconductors themselves.

	Another element that is very common is arsenic, which binds with sulphur to form [[arsenopyrite]] or more rarely oxygen to form [[löllingite]]. These are both great semiconductors.		Another element that is very common is arsenic, which binds with sulphur to form [[arsenopyrite]] or more rarely oxygen to form [[löllingite]]. These are both great semiconductors.
Line 20:		Line 20:

	Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].		Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].

			It's worth mentioning that while quartz has its own particular place in electronics history (not least in the extraction of silicon) it is not a semiconductor, and not useful for our purposes here.

			==Safety==

Cornish semiconductor: /* What to look for */

2026-06-21T15:21:24Z

What to look for

← Older revision		Revision as of 15:21, 21 June 2026
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	Most often in the case of searching for semiconductors, we are looking for metallic mineralisation - the most abundant metal is iron, which is often associated with rarer metals. We are looking for heavy, red or yellow iron stained rocks - often coated in goethite, which is one of the minerals that comprises rust.		Most often in the case of searching for semiconductors, we are looking for metallic mineralisation - the most abundant metal is iron, which is often associated with rarer metals. We are looking for heavy, red or yellow iron stained rocks - often coated in goethite, which is one of the minerals that comprises rust.

	Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla, some of these secondary forms, such as [[chalcocite]] (or grey copper) are also great semiconductors themselves.		Many of the mines here were working copper, which is also very abundant, mostly in the form of [[chalcopyrite]]. The copper oxidises and decays into green and blue minerals like malachite and chrysocolla, some of these secondary forms, such as [[chalcocite]] (or grey copper) and [[cuprite]] are also great semiconductors themselves.

			Another element that is very common is arsenic, which binds with sulphur to form [[arsenopyrite]] or more rarely oxygen to form [[löllingite]]. These are both great semiconductors.

	The other material that Cornwall has become associated with is tin, which was mined for centuries before copper became important. The principle ore of tin is [[cassiterite]] which can also be found in the waste dumps. It is extremely heavy (six times the mass of water) and is also a semiconductor.		The other material that Cornwall has become associated with is tin, which was mined for centuries before copper became important. The principle ore of tin is [[cassiterite]] which can also be found in the waste dumps. It is extremely heavy (six times the mass of water) and is also a semiconductor.

			Other slightly rarer semiconducting minerals include [[wolframite]] (tungesten ore) which has some interesting properties such as [[negative resistance]].