ncat GTJ2 Phosphorite, Okidaito-jima (Oki Daitou; Rasa-tou; Rasa island), Daito Islands, Shimajiri District, Okinawa Prefecture, Japan

Phosphorite is generally either carbonate-rich hydroxylapatite, or carbonate-rich fluorapatite. This specimen exhibits a green afterglow in parts, after being exposed to longwave ultraviolet light.