Hematite is an insulator. But it can be a semiconductor too. It depends of crystal defects like oxygen vacancies and others.
I tested hematite with different electric conductivity.
For this I used a pulse generator with a pulsating voltage of 50 Volt.
After connecting the stones with the output of this pulse generator audible sound could be heard caused by vibrations of the semiconducting hematite stones.
A nearly insulating synthetic hematite didn't generate audible vibrations.
The semiconducting hematite stones from Brazil showed enhanced ferromagnetism.
I tried to prepare this non-stoechiometric hematite by dissolving pure iron in acetic acid and heating the reaction product ferric-acetate. I succeeded in preparing a special iron oxide which looks like hematite but is semiconducting and ferromagnetic. This red powder shows strong electrostriction.