What rock has colourless chunk that breaks apart into cubes and no lustre is soft enough to be scratched by fluorite?

The rock is halite, also known as rock salt. Halite is a mineral composed of sodium chloride (NaCl). It is the most abundant mineral in the oceans and is also found in salt lakes and underground salt deposits. Halite has a cubic crystal structure and typically forms clear or white cubic crystals. It is soft and can be scratched by fluorite, which has a Mohs hardness of 4. Halite is used as a food additive and preservative, and is also used in the production of chlorine and sodium hydroxide.