*2.3. Sample Materials*

A rock can be described based on the content of its mineral components and its fabric (Figure 3). It consists of the individual mineral phases, but often also contains defects (e.g., pores, cracks), which form the continuous phases (gas or liquid phase) and glasses as well as cryptocrystalline masses which are combined to a nondifferentiated phase. Each single constituent of a phase—also termed microbody or grain—takes up a certain volume that is defined by boundary surfaces.

**Figure 3.** Characterization of raw materials.

To introduce the characteristics of the rock fabric in technology assessment, the texture must be expressed in figures. Based on the application of stereological methods, the rock is quantitatively described by means of its


The term "rock fabric", comprising texture and structure, can be understood as the quantity of all geometric data of a piece of rock. The characteristics of the rock fabric, quantified with the help of QMA methods, are based on the formal characterization of the rocks by geologists in order to facilitate understanding between geologists and engineers with their respective terminology.

The texture of a rock is the term used to describe the nature of its composition by individual components. It is dictated by the form of the individual mineral components and their mutual geometric relationships. Accordingly, the grain shapes and the grain sizes of the mineral components are essential elements of the rock texture.

The structure of a rock depends on the spatial arrangement of its components. In this case, the components are less the individual grains and far more complexes of the same minerals or other identical structural elements. In this context, the orientation of the components as the directional texture, the distribution of the same as the distribution texture and relative density (compact and porous rocks) are taken into consideration. Rocks with strata of varying mineral composition therefore have an inhomogeneous distribution texture; lava with gas bubbles is characterized by their incomplete space filling.

For the comparison of QMA and CT three different samples were investigated. Their characteristics, described by mode and fabric, but inherently representing also mechanical properties relevant for comminution, ore content vary widely, to cover a range of materials from metal and non-metal mining as well as the aggregate industry. The need to crush and, to a certain extent at least, grind the material to produce a sellable product is the bracket that connects those industries. The investigated samples contain:


#### **3. Results**

In the following, the results of the QMA and the CT analyses of the three different sample materials are presented.

#### *3.1. Copper Ore*

#### 3.1.1. QMA Results (Copper Ore)
