X‐ray absorption fine structure (XAFS) formation in a silicon crystal is analysed on the basis of a quasiatomic description. The spectral dependence of the XAFS formation mechanism is investigated. The existence is shown of four specific spectral regions with different electron‐optical characteristics of the atomic surroundings and different “size” effect of XAFS formation. It is shown that (i) the sensitivity of XAFS to distant coordination shells is maximum in the interval 30 nm⁻¹ < k < 60 nm⁻¹ and (ii) the combination of single reflections from the surroundings and photoelectron refraction in the surroundings well describes the XAFS in a very large domain k > 25 nm⁻¹.