Hi; I think it is a blow hole Acorn button. 1700's. I could be wrong ok. If you clean it only use light soap and water letting it soak for a few days then use a wooden tooth pick and gently PUSH the dirt off. Do NOT scratch at it ok. This may take a few soakings but you will be happy with the results ok. PEACE:RONB
Hmmmm I would think if it were that old wouldnt it have a shank on it and not notched out like it is? i though all old buttons had shanks but I know nothing about buttons so I may be wrong. Thanks for the info though will be exciting to find out if it really does have some age to it