Knebelite is a manganese-rich variety within the olivine group. It is usually found in typical manganese mines (such as skarns). Fusamata, however, is a granite pegmatite. Knebelite from this type of formation is much rarer than specimens from metamorphic ore deposits. The pegmatites in the Abukuma Mountains (including Fusamata and nearby Suishoyama) were intensively studied in the early to mid-20th century. Many of these sites have been inaccessible or completely overgrown for decades. From an old German collection, specimens like these are almost never offered.. It also shows in a spot a neon-green fluorescent short-wave reaction (see 2 last pictures). It's also interesting for micromount collectors due to the other rare minerals that can occur on the specimen surface.