Shahrokh Mehmood
Geologist & Geoscientist
Essential tips and techniques for field geologists to identify minerals based on physical and chemical properties.
Scientific Foundations of Mineralogy
Minerals are the building blocks of rocks and the foundational materials of our modern economy. For a geologist, mineral identification is a primary skill that combines physical observation with chemical knowledge. Every mineral has a unique crystal structure and chemical formula, which manifest as specific physical properties that can be tested in the field or the laboratory.
The Field Identification Toolkit
Systematic mineral identification begins with physical properties: Luster, Hardness, Cleavage, and Streak. Using a simple toolkit consisting of a streak plate, a steel knife, and a 10x hand lens, a geologist can narrow down a sample to its likely species. For instance, the distinction between hematite and magnetite is easily made using a streak test—hematite leaves a reddish-brown streak, while magnetite is black and strongly magnetic.
Hardness is measured using Mohs scale, ranging from talc (1) to diamond (10). Understanding where common minerals like quartz (7) or calcite (3) fall on this scale is essential for quick field assessment.
Advanced Analytical Techniques: XRD and XRF
While field tests are vital, precision in modern industry requires laboratory analysis. X-Ray Diffraction (XRD) is the gold standard for identifying the crystal structure of a mineral, making it indispensable for analyzing fine-grained minerals like clays or complex mineral assemblages. X-Ray Fluorescence (XRF) provides the elemental composition, allowing us to quantify the purity of ores or the concentration of rare earth elements.
My experience at Northvolt and Lund University involved extensive use of these techniques, particularly when analyzing pre-lithiation materials and battery minerals. The transition from field observation to laboratory precision is where the highest value is added in professional geosciences.
