Final answer:
Calcite is memorable for its double refraction property when in crystalline form.
Step-by-step explanation:
Calcite, a form of calcium carbonate (CaCO3), is known for its double refraction property when in crystalline form. Double refraction is the phenomenon where light passing through a crystal splits into two rays with different velocities. When a transparent crystal of calcite is placed over a page, we can observe two images of the letters, which is a unique characteristic of calcite.