Huge, black, triangular shaped craft. Made no sound & had mercurial lights that changed color.

Myself, brother, & stepfather seen a huge triangular shaped "craft" right after dark while out for a walk in the country where we live.  At first there were no lights. It was black and approx. 1000ft in the air. We had set down on a hillside to look at the first stars, and we noticed the craft because it was darker than the sky.  This was 300-500 from point to point and formed a perfect right triangle.  
After a couple of minutes, 3 lights appeared, one at each point.  The lights changed colors, and appeared liquid, like mercury.  The craft eventually started rotating slowly.  We watched it for several minutes.  
Then it just VANISHED right before our eyes.  It never made a sound.  It gave us the "feeling" that whoever, or whatever, occupied it, was aware we were watching it. V ery strange.  A friend also saw a similar craft several months later in the same county.
Witness indicates that the date of the event is approximate.  PD