Ross tells us, "Our sources were current and former government scientists who were all involved in analyzing the substance in the letter."So according to Ross, his sources didn't lie, they just made a mistake. More details at the link.
...."Their initial conclusion, based on microscopic examination was a brown substance that initially was reported as bentonite. We went back immediately after the White House told us it was not the case. We were told after further chemical analysis it was determined it was a silica, but not bentonite — something they had never seen before but had a brownish color."