Geoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿
Northern Highland #Scotland folk: if you live near a beach it could be worth looking for fulgerite tomorrow, patches of sand that have been hit by lightning. If you (very gently, they're fragile!) dig down you may find a branch-like structure where the lightning fused the sand into a kind of glass. Rare, special thing to find.
Jun 25 at 9:39pmMastodon for Android
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿16h ago
There's a similar sand-to-glass thing called Trinitite. I've got about a gram of it. It dates to precisely 05:29 local time, 16th of July 1945. It was created by the detonation of the first nuclear weapon.
Illegal to collect from the site these days (and most of it was buried elsewhere to prevent that), but buying/selling/owning samples collected before the ban is legal. Still *faintly* radioactive, but no more than some things you can buy in supermarkets. But don't eat it, cos alpha.
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿16h ago
I did a Geiger counter test out of curiosity, it's about 15% above background here. Low-sodium salt from the supermarket, to put on your chips, is about 50% above background.
Doesn't guarantee it's safe though, the test doesn't discriminate between alpha, beta and gamma. Potassium chloride salt is mostly beta, so meh on eating it at that level. Eating alpha emitters is always dodgier at any level, if that's what I detected.
Show threadBashStKid16h ago
@_thegeoff Try it through paper and then tinfoil for a very basic alpha/beta blocker?
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿16h ago
@BashStKid I'd need to do very long tests (multiples at hours a time) to get anything statistically significant. For my purposes, which are "is it actually radioactive, and am I safe having it in a jar on the shelf?" my test is enough ;)
Show threadgahlord16h ago
@_thegeoff I feel like this is a part of a Tom Clancey novel
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿16h ago
@gahlord Oddly, one of my favourite books as a kid was Angus MacVicar's "Return To The Lost Planet", where kids visit a deserted alien world and realise there was a nuclear war, from all the green glass in deserts. Written in 1954 by someone who served in WWII.
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿15h ago
@gahlord Also, as a book that was already 30 years old in the 80s, it smelled *amazing*.
Show threadMartin Rundkvist1d ago

@_thegeoff
Lightning strikes also leave a permanent radiating structure in the soil that is visible in magnetometry. Those have confused many archaeologists since the tech became available.

#geophys #archaeology

Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿19h ago
@mrundkvist I've always wondered how magnetite can end up with a magnetic field far, far stronger than Earth's. My only idea is high currents due to lightning strikes.
Show threadBeeCycling1d ago
@_thegeoff Fulgurites are so cool.
Show threadJanet1d ago
@_thegeoff Hot tip! Wait until the lightning ⚡️ has finished before starting to collect…
Show threadGeoff 🏴󠁧󠁢󠁳󠁣󠁴󠁿17h ago
@Janet_52square Good point, well made 🤣👍
Show threadColin Purrington1d ago
@_thegeoff If anyone needs pics of sand fulgurites: https://oumnh.ox.ac.uk/fulgurites
Fulgurites

It is astonishing to think that a split second of stormy weather can be captured in stone. This is is exactly what happened when a bolt of lightning struck drifting sand near Drigg, in Cumbria, and the intense heat fused the sand grains together.