Which color was NOT an original M&M?

Orange M&Ms joined the party in 1976 to replace red ones which fell victim to public fears about Red Dye #2 even though it didn't even have any. But, a public freakout is a public freakout and so Mars decided to just roll out the new color, joining tan, green, yellow, and brown in an awfully earthy candy bag. Red made its triumphant return a decade later in 1987, and Mars decided to keep orange alongside it.