[ARC5] Crystals and WWII

[Dennis Monticelli]

Twinning of crystals is just when separate crystals share some of the same
crystal lattice.  In other words, when two crystals inter-grow    You've
all seen photos of inter-grown crystals of quartz or other minerals.   But
sometimes the twinning is not visually obvious so it gets sliced across the
shared region and that rock won't do its piezo thing.  There are more
sophisticated optical and radiation tests that can be performed to weed out
the twinned material so later in the war effort, that's what they did.  The
equipment for doing this was shipped to Brazil so only good stuff would
take up precious plane weight.  Yes, they had to fly it to the US because
earlier in the war a U-boat sank a freighter that happened to be carrying a
large shipment.  That sinking caused such a severe shortage that US makers
had to reclaim crystal stock from their scrap pile.

Dennis AE6C



On Sun, Mar 17, 2013 at 7:22 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> Okay,
>
> What is twinning? Twinned with what? I know what twins are but crystals
> weren't born. They um... crawled out from under a rock.
>
> befuddled,
>
> Bill  KU8H
>
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