chalkstone

From chalk +‎ stone.

chalkstone (plural chalkstones)

1. (obsolete) A mass or piece of chalk.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Isaiah 27:9:

     [W]hen he maketh all the stones of the altar as chalkstones that are beaten in sunder, the groves and images shall not stand up.

2. (medicine) A chalk-like concretion, consisting mainly of urate of sodium, found in those affected with gout; a tophus.
   • 1794 January 23, Hester Lynch Piozzi, Thraliana:

     [T]he thoughts of his breeding Gout so fast shocks me: it has beside all the rest made a Deposit in the Great Toe—I mean in the Joint, as if intending a Chalkstone.

• Shackleton, shecklaton