Kolang (Hammerstone) - CM1/2 Carbonaceous Chondrite

Kolang is a witnessed CM1/2 Carbonaceous Chondrite fall from North Sumatra, Indonesia, which occurred on 1 August 2020. The fall became widely known because one stone struck through the roof of a house in the Kolang district, making it both a witnessed fall and a ‘hammer’ meteorite. With a reported total known mass of around 2.55 kg, Kolang is especially significant as the first recognised witnessed fall of the CM1/2 type, a rare and highly water-altered Carbonaceous Chondrite classification.

Kolang specimens are typically dark, fine-grained, and fragile, reflecting their Carbonaceous composition and extensive aqueous alteration. Its classification as CM1/2 indicates material ranging from areas where chondrules have been almost completely replaced by hydrous silicates to areas more typical of CM2 meteorites. Published descriptions note that Kolang is strongly brecciated, meaning different pieces can show noticeably different textures and levels of alteration.

Studying Kolang provides valuable insight into water-altered primitive asteroid material, Carbonaceous Chondrite diversity, and the preservation of fresh material from a modern witnessed fall. Its rare CM1/2 classification, Indonesian provenance, roof-impact story, and limited recovered mass make it especially desirable for collectors of Carbonaceous Chondrites, witnessed falls, and hammer meteorites. Each specimen represents ancient, volatile-rich solar system material delivered to Earth in a clearly documented event.