Unsolicited offer to buy minerals in Reeves cty

we were contacted by a landman for Tularosa oil asking to buy our interest. this is property from my great Aunt that we knew nothing about! but all i can find is a royalty deed dated 7/14/1950 how can I find out if there is another deed out there? this is blk c1 sec 2 PSL This is all the info I received! Steven Allen