✍️🪨⚪

#calcium carbonate #chalk #blackboard chalk #writing chalk #school supply #rock dust #white chalk

✍️⬜🪨

#chalk #writing chalk #sidewalk chalk #blackboard chalk #mineral powder

⬛✍️⚪

#chalk #writing chalk #blackboard

✍️⬛💨

#chalk dust #writing chalk #kapur tulis #sekolah #papan tulis