1976 bronze triangle seen in nashville, tn

this is a report that my niece made to my family in 1976.  She was walking across the parking lot of an apt house on haywood lane, when she became aware of a large, bronze triangular craft floating right over her head. she said it was completely silent.  she stood in awe watching this thing until it flew past her. she said nothing about lights or any other traits, just that it looked to be bronze and it was a triangle.
my niece has a very high-IQ and is not known to report anything like this for any reason other than to report what she has seen.  about 20 years later, i happened by 'coincidence' to find another person in the Briley Pkwy area of Nashville who claimed to have seen the very same thing during the same year.  (I had to approximate the time of sighting)
Date is approximate.  PD