well, if you put blood in an air-tight glass and wopped it underground, some looser with a... 'glass jar detector' would be wandering along the beach on a rainy saturday evening, (what a loser), and then BLAM! his little detector would start having an orgasm, and then he'd dig it up and call over one of his loser mates, and they'd be like, 'wow! we're finally gonna get something, oh i think i can feel it, i've, i've got it : ) .... oh... it's a jar full of blood, which bell-end buried this a thousand years ago?' HOWEVER, if he found it to be a gold jar, he's be like, 'wo! gold! mint! let's melt it down and make earings and sell it and be rich! oh christ it's full of blood, which bellend buried this a thousand years ago? who cares, we're minted :)' thats what'd happen, and they've had glass for ages, hence glass windows in castles and the like