"I saw a big battery with six dynamite sticks wrapped around the battery. And he said to me, 'All I have to do is attached this wire to this gadget here and we'll all be dead. - Florence Schaffner
Been reading through the McCrone particle data on the tie, prompted by Snowmman's interest in the Palladium. I found a significant number of relatively identical (please ignore the oxymoron) particles of note in the "Silicon Rich" category. They all contain just over half Silicon, a quarter Magnesium, 10-15% Palladium and the rest Aluminum. In searching for an application for these elements in combination, the only result I am getting is ignition/detonation wire.
There's a product known as PyroFuze that is used for remote ignition of explosives, pyrotechnics, hobby-store rocket igniters, etc. It's an alluminum or magnesium wire coated in palladium, specifically for use with battery ignition.
A "bridgewire" like this is commonly coated at the end in a pyrogen agent, often black powder suspended in cellulose. Black powder would contain potassium and sulphur together, two elements found in at least 30 particles I've found so far, and the 140 particles of pure Antimony I'm seeing would almost exclusively be found in a diode, also used in constructing a pyrotechnic igniter.
It's possible that many of the weird particles we're looking at are Cooper's bomb making materials (yikes!) as well as debris from scavenging for the parts. I have found at least one patent for a fire extinguishing unit from the late '60s that both used bridgewire and Potassium Chloride (K & Cl, also found together on the tie) that was designed specifically to be built into appliances like television sets, which contained cathode ray tubes.
Anybody else want to dig in and see what we can find?