Geoffrey I of Anjou ( c. 938\/940 - July 21 , 987 ) , known as Grisegonelle ( `` Greymantle '' ) , was count of Anjou from 960 to 987 .
Geoffrey I of Anjou ( 930-987 ) , called Greymantle ( French : Grisegonelle ) , was a French nobleman who was the Count of Anjou from 960 to 987 .