Julian Cope presents Head Heritage

These are pictures of the kind of necklaces you saw, I guess.
http://nms.scran.ac.uk/database/results.php?offset=37&no_results=12&scache=41jiz2au42&searchdb=scran&sortby=&sortorder=ASC&field=&searchterm=%2BJET

They are usually found in burials from the bronze age, older women usually, I was told at the museum, and more common in Scotland than elsewhere. There was a small amount of jet from Mull and those islands on West coast, but most jet came from whitby.

I'm supposing jet is sacred as an inbetween thing, neither stone, nor wood, with electrostatic properties. It would have been an easy thing to carve, at any rate. I find it easier than wood in many ways. Though more delicate.

Jet had connections with bear/serpent religious practices too. Ancient writers recorded the beleif that it protected and cured serpent bites, for instance, or could be used as a test for virginity! Little carved bear charms or talismans, or just toys (we love our teddy bears still), used to be left in graves of children (bear goddess is the foster mother of mankind).

This is just a cute bear pic, lol
http://i.treehugger.com/images/2007/10/24/playful-polar-bear-001.jpg

Jet is supposed to absorb a person's aura, the necklaces might have had something to do with that, keeping a little part of the person behind by the grave for ancestor worship, maybe. It was used as mourning jewellery much later in Victorian times the same way, but the living kept some hair from the deceased in lockets of jet while they were in mourning, so their aura was with you always, not by the grave. I've been commissioned to make replicas of those necklaces for people who have altzeimers in the family before, as they think it will help them remember who they are longer.

http://whitbyjet.net/definition.html

This website has a clear description of how yet forms, and why the centre of the tree trunk keeps its grain and shape more tha the outside, becoming siliconised instead of compressed.

This site below has more.
http://www.britarch.ac.uk/ba/ba70/feat3.shtml

I found this fact most interesting:

We can tell by the degree of wear that some of the jet pieces probably came from 'heirloom' necklaces already 200-300 years old by the time they were reused.

Makes me wonder if the necklaces were broken when put in the grave, and some of the essence of the person given to descendants in the form of some beads to start their own necklace.

and this:

Most of these necklaces come from graves, and where the sex of the deceased has been determined, it is allegedly almost always female. However, at Tara in Ireland, one was definitely worn by a young man

Shows it wasn't just women. The Greeks said jet was sacred to the moon goddess, and perhaps its wearers were devotees, mostly, but not always, women.