Spherical object at great height moving at high rate of speed from south to northI am a freight pilot and my route takes me from Reno to Elko, NV. On the 29th of December at approximately 1400 hrs. local, I was leaving the FBO and walking to my plane. The day was severe clear and crisp. There were a few contrails crossing and nothing else. I saw one of the linemen, looking up at the sky. I asked what he was looking at and he directed my eyes to an object so high up it seemed to be against the blue of the sky. The object looked like the ball at the end of a pushpin held at arm's length. It was the color of quicksilver and looked perfectly spherical. It was moving from south to north and we saw it pass behind a number of contrails; some of which had to be in the FL400 range. One more lineman came out to see the object and we observed it move north for about 15 minutes all told. In the end, it simply vanished and we could not locate it anymore. I think whatever it was had to be huge to appear that size to me. The object didn't shimmer, shine or give off any sort of light. I've no idea what it could have been.