Rocks can be described as:

Rocks are primarily defined as consolidated mixtures of minerals. This means that rocks are composed of various minerals that have combined and solidified over time. Each mineral within a rock has a distinct crystalline structure and chemical composition, and the combination of these minerals can create a wide variety of rock types, including igneous, sedimentary, and metamorphic rocks.

Understanding that rocks are aggregates of minerals is fundamental in geology, as it highlights the intricate processes that lead to rock formation, such as cooling and solidification of molten material to form igneous rocks, compaction and cementation of sediments for sedimentary rocks, and the alteration of existing rocks under heat and pressure for metamorphic rocks.

The other options present ideas that do not accurately describe what rocks are: pure metals do not encompass the variety found in rocks, liquid geological material refers more to magma or lava rather than solid rock, and solely organic materials are characteristic of certain sedimentary deposits like coal but do not represent the broader definition of rocks. Therefore, the most accurate description is that rocks are indeed consolidated mixtures of minerals.