Ferrite particles, electrophotographic developer carrier core material, electrophotographic developer carrier, and electrophotographic developer

A ferrite particle,

• comprising a crystal phase component comprising a perovskite crystal represented by the compositional formula:
• RZrO3, wherein R represents an alkaline earth metal element, and
• having an apparent density in a range represented by the following formula:
• 1.90≤Y≤2.45
• provided that Y in the formula is the apparent density (g/cm3) of the ferrite particle, wherein the ferrite particle contains 0.1 mol % or more and 3.0 mol % or less of zirconium and
• wherein the perovskite crystal constitutes 0.05% by mass or more and 2.50% by mass or less of a crystal phase constituting the ferrite particle is determined by a Rietveld analysis of an X-ray diffraction pattern.