Japanese carved fan

Cleaning out my grandmother's house, we found a carved Japanese fan mounted and sealed inside a display box. Based upon your comments for identifying if something is ivory or bone, it may be ivory, but I do not see all that I think I should, and it may be synthetic. Uncle traveled to Japan in early 1980's and brought several things back. Don't know if this is one of them, but know he was a collector and did not purchase things without art or resale value as a normal rule. Couldn't find anything online that was a match to this.