Got some ideas from you tube last night.

I will go with leaving the charcoal in the paper bag it came in, loosely wrap the paper bag with an old sheet I have that I have been cutting up for rags, loosely loop a rope around it from top to bottom. Place it on the driveway and run back and forth over it with the car tire. Check it by feel through the wrapping to see what size I have it down too. Finish off a larger chunks with my pointed end of my slate hammer.

I have done slate work on roofs in the past from complete installation to individual replacement.

Have a story to tell about their telling that charcoal will last for ages.
During my construction days I was digging soil out to put a footing in for a garage. I was down about 6 feet in yellow sandy soil that did not look disturbed for ages. Took a shovel full of soil and opened up a circle of charcoal that looked like an old campfire about 18 inches in diameter. There was charcoal dust as well as little pieces of charcoal. I did not see anything other than the charcoal from the campfire. Can you imagine how old that campfire was and who sat around it cooking their meal and maybe for warmth depending on the season at the time.

Another story about finding ancient things.
I was working as a laborer in my early years about 55 years ago for a builder installing pipelines in the new housing project. While down in the trench working about 6 feet down I spotted a flint spear head about 6 to 8 inches long and about 2 inches wide at the widest point. Can you imagine who the flint knapper was and the hunter who used and lost it somehow. Must have been ages ago before the white man arrived.