Some of you are on the right sort of track to the answer to Friday's geopuzzle, but I think that I can clear up the uncertainties considerably by demonstrating exactly why this particular rock is staying well away from my lab.
Here's an innocent compass:

And here's what happens when my new deskcrop is placed nearby:

One of my companions on last week's trip suggested that we could have a lot of fun trying to get first year undergraduates to measure the bedding orientation in the locality this sample was retrieved from. How deliciously evil.

Chris Rowan is a geologist specialising in the dark arts of paleomagnetism, and getting people to pay him to travel to exotic destinations for fieldwork. Having drilled up New Zealand during his PhD, and South Africa in his first post-doc, he now works at the University of Edinburgh.
Anne Jefferson has a love of all things water-related and blends hydrology, geomorphology, geology, and climate change in her work. She has a Ph.D. from Oregon State University and is now an assistant professor at the University of North Carolina at Charlotte.
Comments
That's one massive piece of magnetite?!?!?!
Posted by: Mathias | February 3, 2008 1:31 PM
Obviously, it is an orc, which is why the compass is clearly glowing blue when you put it near the deskcrop. That would also explain why it is compelling you to commit evil against innocent halflings undergrads.
(Seriously, I'm going to have to second Mathias' guess of giant piece of magnetite.)
Posted by: Julian | February 3, 2008 1:50 PM
Cumulate magnetite.
Posted by: Andrew | February 3, 2008 3:02 PM
Did you re-balance your compass, or is that a local S.H. one?
Posted by: Lab Lemming | February 3, 2008 6:07 PM
It's a local one.
Posted by: Chris Rowan | February 4, 2008 10:18 AM