Which description correctly characterizes rocks with chemical/biochemical textures?

• A. Biochemical rocks form from shell fragments only.
• B. Rocks with chemical/biochemical textures indicate precipitation in water, such as limestone or rock salt.
• C. Clastic rocks are formed by chemical precipitation.
• D. Organic rocks are formed by metamorphism.

Answer: (B)

Rocks with chemical or biochemical textures form when minerals crystallize from water, either directly precipitating from a solution or through biological processes that promote precipitation. This happens as ions in seawater or groundwater come together and settle out, building rocks that show interlocking crystals once the water leaves. Limestone and rock salt are classic examples because their minerals precipitated from watery environments, leaving distinctive chemical textures. Biochemical textures are related to organisms influencing the precipitation process, but the unifying idea is that the rock records minerals that formed from solution rather than from fragments of other rocks. This is why these rocks contrast with clastic rocks, which are made from cemented-together pieces of preexisting rocks, and with organic rocks or metamorphic rocks, which form through different pathways.