LSD contains mainly spectra of clay minerals, extracted from naturaly occuring rocks by a sequence of physical and chemical treatments aimed and obtaining pure, monomineralic samples. Depending on the mineral and parent rock type, extraction procedure was modified, however, in general it consisted of the following steps:

• Mechanical disintegration of a parent rock
• Dry sieving
• Selective dissolution of impurities: organic matter, carbonates, and iron (hydro)oxides by treatment with hydrogen peroxide, sodium acetate - acetic acid buffer solution, and sodium dithionite, respectively.
• Dialysis
• Further size separation in a centrifuge
• Dialysis and drying

The above procedure was adapted from soil studies and is often reffered to as a “standard procedure” in the soil science literature. Any modifications of the standard procedure are indicated in an experiment's descritpion.
As for December 2017, LSD contains mostly spectra of two groups of clay minerals: smectites in H₂O- and D₂O-wet states under various relative humidity and chlorites heated in-situ up do 800°C.