The sample was prepared by drop casting 1 µL from a suspension of hematite particles in mixed 1:1 isopropanol -pure water onto a 50 nm thickness SiN membrane. Figure presents the spectrum recorded from one isolated hematite particle. We used aXis2000 software to analyze the STXM data. Despite the noise present in the data recorded from a single < 50 nm nanoparticle, we can compare it to the corresponding atomic continuum using the optical density expression 𝑂𝐷 = 𝜇(𝐸) • 𝑑 , with 𝜇(𝐸) the energy dependent linear attenuation coefficient and 𝑑 the thickness of the nanoparticle. The linear attenuation coefficient varies as a function of the X-ray wavelength, 𝜆,