**Figure 3.** *TG and DTG curves of Admontite mineral (MgB6O107H2O).*

Thermal behavior of magnesium borates is related to hydrate groups in the structure. For the hydrated magnesium borates, thermal decomposition process begins with the dehydration reaction which means to split off the crystal water (*x*H2O), and continues with the dehydroxylation reaction which means to split off hydroxyl anions (OH) as a water molecule. With the increasing temperature, phase changes can also be seen.

As a typical example, thermal curves of TG and DTG for Admontite mineral between 25 and 750°C are presented in **Figure 3**. Admontite (MgB6O107H2O) mineral has lost its 7 moles of crystal water with a two-step reaction. In the first step, the reaction occurs in the range of 40–125°C, and the peak of DTG curve is seen at 116°C. The second step of decomposition emerges in the range of 125–570°C and the DTG peak is seen at 230°C. The mass losses of the first and second steps of decomposition are determined as 11% and 25%, respectively.

For the dehydrated magnesium borate, only phase changes can be seen or the compound stays stable. This stability could be related with the reaction temperature of fabricated dehydrated magnesium borate.
