**2.2 Rock structures**

Most rocks are not uniform all the time. On a scale best measured in millimeters or centimeters, they are made up of individual mineral grains that differ in size, shape and composition. The geometric properties of these small rock features and the relationships between them form rock texture. Rocks also commonly differ on larger scales, and are best measured in centimeters to meters to kilometers. The disparate and small-sized individual features of the rocks are called "structures". Our mission is to find out if there are rock structures that can provide clues to the formative environment of rocks: whether they are igneous, sedimentary or metamorphic.

There are many rock structures. Geologists usually divide them into "primary" and "secondary" structures [4].

