Cleaned it up a bit for you.
Well-thought idea! At least it's a 'normal thing with a weird property', and not some 'fightan good' or 'invincibles'.
So, is it actually falling the wrong way, or just caught in a very low orbit?
What makes this rock more than just an anomalous object?
Okay, seriously… Magnetic East?! What the hell is that going on about?
And yeah, it's just something weird, so why is it an SCP and not just an anomalous object, like Quikngruvn said?
Does it accelerate or reach a constant speed? (Is it falling or orbiting?)
I would take this to a magnetic pole and release it. (No east at the south pole!) Then I'd make this an Anomalous Item as Drewbear suggests, because it's not very CP.
This is actively bad. Too short, I don't think magnetic east is a thing that exists, the item is too boring, the tone is off (words like "simply," "ordinary", etc. don't belong in documents), and it ends in a goddamn humorous researcher note. Thanks to Mafia_Puppet for pointing this one out to me so I could cancel his/her/its vote.
edit: Let me explain the tone thing further:
For all intents and purposes, SCP-283 is an ordinary rock,
For all intents and purposes? If the thing is attracted to a gravitational field only it can detect based on a direction that doesn't exist, that is (to the extent that this shitty phrasing can imply such) an intent and purpose in which this is not an ordinary rock. So the phrase doesn't have any meaning here and should be replaced. The fact that it both doesn't apply and, in fact, actively contradicts the purpose of the document is indicative of the fact that "for all intents and purposes" is a colloquialism and doesn't belong in a scientific document. Try again.
The pictured stone isn't really dark gray. It's more beige than anything.