Mineral thermal analysis is the study of behavior of minerals as a function of temperature. It is used to elucidate the physical and chemical properties of minerals as well as the origin and evolution of rocks and geologic structures. The primary method used in mineral thermal analysis is called differential thermal analysis (DTA), wherein a sample is heated in the presence of a reference material and the differences in the temperatures of the two components are recorded. This technique is used to measure the temperature at which the component minerals undergo phase changes due to the removal or addition of heat.
The process of mineral thermal analysis is complex, and the amount of data produced requires sophisticated computer programs to interpret the information. Consequently, mineral thermal analysis is usually employed in conjunction with other analytical techniques such as x-ray diffraction (XRD). XRD is often used to identify the mineral composition of the sample, and the DTA results are then compared to the XRD results to obtain an understanding of the physical and chemical properties of the minerals.
In DTA, the sample and the reference material are placed in a furnace and heated together. As the temperature of the sample and the reference material increase, the two components will undergo different temperature changes. The difference in the temperatures of the two components is measured and recorded, and the recorded data can then be used to indicate the thermal stability of the components and their relative susceptibilities to heating and cooling.
The DTA data can be used to identify the temperatures at which various minerals undergo phase changes. For example, the melting point of a rock can be determined by measuring the temperature at which the mineral composition of the sample begins to change. The temperatures at which specific minerals crystallize and recrystallize can also be determined by using the DTA data.
The phases of solid materials can also be determined by using the DTA data. For example, the compound known as wollastonite can change from an amorphous phase to a crystalline form during the heating process. The DTA technique can be used to identify the exact temperature at which this transformation occurs.
In addition to determining rock properties, DTA can also be used to pinpoint the source of a mineral sample. For example, a specific mineral can be identified based on the temperatures at which its components crystallize and recrystallize. This information can then be used to determine the location of a mineral deposit.
Finally, DTA data can also be used to investigate the origin and evolution of rocks and geologic structures. The temperatures at which various minerals undergo changes can be used to identify events, such as metamorphism, that have occurred in the history of the rock or geologic structure.
In conclusion, mineral thermal analysis is a powerful tool that can be used to characterize and investigate the physical, chemical, and origin of rocks and geologic structures. DTA is the primary method used to collect and interpret the data produced by the technique, and sophisticated computer software is used to analyze and interpret the data. Mineral thermal analysis can be used to determine the melting points, phases, and source of a mineral sample as well as investigate the origin and evolution of rocks and geologic structures.
