My mother told me if I have an upset stomach I should eat writing chalk.
The informant thought that her mother thought calcium is like the drug tums so same it is the same idea. Her mother is Slovenian. She though the chalk would be impure and gross so she never tried the chalk.
Slovenia is known to have many natural chalk streams in the country. All the natural chalk must be in abundance so the people must utilize it as common resource. Because of its availability, some people might have used the chalk as a calcium supplement. I am not sure however, how calcium is supposed to make someones stomach feel better.