At least that's what I've always called it. The hard deposits you occasionally find in a set of castors. I'm used to finding a stone or two, but I believe I've set a personal record. Just a touch shy of a quarter pound out of the one beaver.

I've always busted it up to use for lure. Always felt it smelt stronger than regular castor, but that may all be in my head. What do you folks do with it?

Never I have ever found them. I have skun a lot of beaver over the years.

Ive caught my fair share of beaver and have never got barkstone castor. Maybe it's just my area I don't know.

Usually have 2 or 3 annually.

I think I have about 4 or 5 sets in the freezer now.

I got one long ago. The thing was so old it defected on land.

My understanding is
Age
Diet
Activity level

So I guess it’s just a guess..

I agree with Vinke to a degree.

I suspect it is a combo of age, diet and endocrine health of the animal. Probably somewhat like a human who develops a chronic issue of kidney stones.

Had a old acquaintance years ago that was spending once a month in the ER for kidney stone problems.

That's interesting. I found three castors today, out of about 10, with varying amounts of barkstone. These were from two different ponds. I usually find a set or two every year. Im guessing that you, Vinke, and Turtledale have all killed a bunch more beaver than I have.

It is something in the water up there. Look what it does to the women in that region.

Yes sir it must be diet or the water. It is interesting though, I'm glad you posted this Sam. Something to look for in the future.

I usually get one about every other year. To me they don't smell as good or strong as regular. Probably something like Bob Jameson's idea.

Think ive only had 3 in my life. Biggest was a tad over 16 oz.

Doing adc in the same spots year after year for over 2 decade's though i run into very few old beaver anymore which might be the reason i don't see them very often.

I never have seen that before and have collected castors for many years. Interesting!

Never had a bark stone in my life. I never was a trapper like a lot of you on here. I caught my share of flat tails both bounty and harvest methods. Kind of cool. Reasearch problem beaver around structures as well as otter restoration but never a barkstone

I, generally, dry castors whole so I'm not sure what's inside them. Have skinned a few thousand beaver and never stumbled across any that I am aware of.

I can usually tell without opening them up. The castor is either rock hard, or feels like it has gravel in it.

Thanks everyone for contributing. This is a fun conversation.

Johnny thorpe made a beaver lure called "barkstone beaver"