This set includes two important samples of regolith engineered to be chemically and physically identical to the surface dust of planet Mars.
Martian Global Regolith Simulant is a global average of surface dirt based on data collected by Curiosity and Opportunity rovers. It was developed so NASA/JPL could prepare for Martian missions by testing rover wheel designs, growing crops, and making bricks with the material. It gets its distinct red color from the relatively high iron content.
Jezero Crater Regolith Simulant is based on the surface dirt of the Perseverance 2020 rover landing site in Jezero Crater. This material is slightly paler that the global average due the specific mineral composition as observed by the Mars Reconnaissance Orbiter (MRO). This site is thought to be the bed of an ancient lake.