I've been poking around with magnetic sediments recently. There's a bit "to-do" going around Quaternary geology circles regarding a potential bolide impact during the Younger Dryas -YD - (ca. 13,000 years before present - YBP). Whether or not this actually happened, and whether this has any lasting climate and ecological impacts have yet to be sorted out. However, the presence of magnetic materials in high concentrations in sediments from the YD is intriguing purely from an academic standpoint. So I've been poking around the late Pleistocene (ca. 20,000 to 10,000 YBP) sediments in the UMV, looking at what's in the magnetic fraction.
So far things look interesting - no confirmation of micrometeorites or other impact debris, but definitely lots of magnetic materials in certain layers. The difficult part is going to be analyzing these grains under an electron microscope or some big machine to see what they're made of.
Here are a few pictures of the extraction process (these are slightly modified from A. West's methods link to PDF)
The bulk sample - the small bucket contains another sample that I dried at about 100°C to determine moisture content of the portion soaking in water.
The basic method involves sticking some strong magnets in a bag...
...then placing the covered magnets into the wet sediment slurry to pick up magnetic grains.
Withdrawing the magnet reveals a big batch of magnetic grains stuck to the outside of the bag. These are placed in another container of clean water. Pulling the magnet away allows the grains to fall into the clean water.
Some of the extracted grains. Once the water evaporates, I can pick out individual grains (with a small, moistened brush or needle).
I haven't started extracting individual grains yet - I'm in the process of refining my extraction and separation methods - doing this all by hand is both slow and not as systematic as would be preferred.