Dear Rabbi Simon
Do you have any information on koshering granite work surfaces in the kitchen for Pesach?
See https://www.thekosherchannel.com/passover-cleaning.html#step and particularly #7, Marble Counters. Granite is the same. Covering them is popular in many circles but not actually required.
If the “granite” is actually composite, ie not a single slab of polished rock but actually pieces of granite (or similar) glued together (sounds unglamorous but it is a cheaper and widespread alternative) there are stronger grounds to say that the surface should be covered. However even there, hagalah (pouring boiling water) may be sufficient. The actual requirement to cover the surface is doubtful. So the choice is yours. Many stringencies are commonplace when it comes to Pesach, yet the basic halakhah is not as demanding. It is worthwhile to read the guidelines from Rav Scheinberg in full.
Rabbi Rashi Simon