just after midnight ,craft travling about 45 mph,at 100ft from north to south on the west side of the waste dumps at pima mine 30 miles south of tucson at dump height ,very low. Craft was flat disk with bluish ionized layer on skin with teardrop shaped tail,the color of a well adjusted gas flame. craft made a rocking back and forth motion ,was under flight controll , Headed tward N.M. I was only 100 FT from the craft. The week before another craft came S to N and made an apparent right angle turn to the east at about 100 MPH then vanished.There are several very high voltage high power lines suplying power to the mine plus a continual thermal updraft from the open pit copper mine.