Thursday, December 4, 2014

How much does a millstone weigh?

Not far from the college where I teach is an old millstone laying decoratively on the ground.

I've been doing some research on millstones lately so I was wondering how much a typical millstone like this would weigh.  Measuring it gives the following dimensions:

   Diameter = 53 in
   Thickness = 8 in
   Hole = 13 in square

This millstone happens to be made of Shawangunk conglomerate which is composed almost entirely of quartz.  All geologists know the density of quartz which is 2.7 g/cm3.  I want to keep everything in more familiar units so that corresponds to about 0.1 lb/in3.

The volume (V) of the millstone would be:

   V = π (d/2)2 t

where d is the diameter of the millstone and t is the thickness.

   V = 3.14 (53 in / 2)2 (8 in)
   V =  17,641 in3

We have to subtract out the volume of the square hole in the middle (13 in * 13 in * 8 in = 1,352 in3)

   V = 17,641 in3 - 1,352 in3
   V = 16,289 in3

Now we can multiply this by the density of quartz to get the weight of the millstone.

   Weight = 16,289 in3 * 0.1 lb/in3 = 1,629 lb

Over 3/4 ton!  Imagine moving this many miles, over rough terrain, with man power, a wagon, and maybe a mule or two.


  1. Which is why they cost about $2000, if you can find one

  2. Do you have any data on the dates these millstones were mined? Before steamboats and railroads it would take quite a bit of effort tyo move these big rocks!

    We have similar outcroppings to make millstones in East Tennessee and the earliest grist mills appeared in the late 1700s. While the French Burrstones may have been easily delivered in the 1880s, the earlier mills used local product which was claimed by the State Geologist in 1855 to be as good as the French burrstones.

  3. Mid-1700s to mid-1900s. Started before railroads and were originally moved by sledge and horse-drawn carts.

  4. May I have your permission to use the photograph of the millstone in an article I am writing? I will of course credit it to this blog.

  5. Replies
    1. And that has relevancy to my post in what way?

    2. Mark 9:42-48 “Whoever causes one of these little ones who believe in me to sin, mit would be better for him if a great millstone were hung around his neck and he were thrown into the sea. And if your hand causes you to sin, cut it off. It is better for you to enter life crippled than with two hands to go to hell, to pthe unquenchable fire. And if your foot causes you to sin, cut it off. It is better for you to enter life lame than with two feet to be thrown into hell. And if your eye causes you to sin, tear it out. It is better for you to enter the kingdom of God with one eye than with two eyes to be thrown into shell, ‘where their worm does not die and the fire is not quenched."

      There is a horrible judgment coming and the wrath of God on this earth and every sinner because we sinned and rebelled against holy and righteous God who creted us. The wrath of God coming on every sinner, who didn't turn from his sin to Jesus. And Jesus used this example with milestone so that we can see how horrible the judgement will be. Therefore embrace Jesus Christ as your savior. He, the Son of God, pure and innocent went freewilling to die horrible death on the cross. He suffered the righteous and holy wrath of God, which sinners deserve and was resurrected. Now, you can also flee from the wrath of God to his loving and merciful hands, when you turn from your sinful life and put all your trust in finished work of Jesus Christ.

      "Whoever believes in the Son has eternal life; zwhoever does not obey the Son shall not see life, but the wrath of God remains on him."

      May God bless you and redeem you.

  6. It's ironic that the self-righteous individual made the post above. I searched what the weight of a millstone is expressly because of doing research on that scripture. It's also ironic that presumptuousness is a sin worthy of death. Maybe in time they will gain accurate knowledge and do something productive with it.

  7. Thank you for this calculation. We have two millstone halves with identical dimensions that were put in place in 1912 as steps off our front porch. They were tilted and sunken and we finally tackled the job of putting them back in place. Interesting to know the approximate weight we were dealing with. Our house was the miller's log house in the 1820s. The 1912 owner was still running the mill but obviously had extra millstones lying around...there are three more in the landscape from that era. (Location: west central Ohio)