The Ancient Onyx (also known as the Black Chaos Emerald) was a large, black colored gemstone located somewhere in Soumerca near the Mystic Ruins in the Mysterious Cat Country. Though somewhat similar to a Chaos Emerald, it is also noticeably different. It served for a time as the prison of Chaos and Tikal, and has been regarded as a sacred artifact by Chao, Felidae, and members of the Wolf Pack Nation.
The Black Emerald and a group of Chaos Emeralds near its resting place were worshipped by a group of Chao and protected by the water creature Chaos. After Chaos went rampant and wiped out the Knuckles Clan, the Seven Server Chao absorbed Chaos' energies, transforming into the seven Super Emeralds, while Tikal then imprisoned both herself and the weakened Chaos in the Black Emerald. Hundreds of years later, Dr. Eggman cracked open the Black Emerald, thus releasing Chaos from his captivity along with Tikal. From there, Dr. Eggman unleashed Chaos as his personal water demon, nearly destroying Station Square. After Super Sonic and Knuckles worked together and defeated Perfect Chaos, the water demon and Tikal returned to their imprisonment in the Black Emerald. Additionally, the Super Emeralds transformed back into the Seven Server Chao, who went with Tikal and Chaos into the Black Emerald. (StH: #79, #80, #82, #84, SSS: #13)
Point of Conflict
The Ancient Onyx later became a point of contention when tensions rose between the Felidae and the Wolf Pack Nation, both of whom claim the gem to be a sacred object in their respective cultures and rightfully theirs. In the traditions of both peoples, the Onyx had helped their ancestors to survive tumultuous events, thus leading to its revered status. This eventually led to an armed confrontation between the two parties when the Black Emerald went missing, with Sonic the Hedgehog and Sally Acorn caught in the crossfire. Fortunately, the culprits were soon exposed as a chapter of the Dark Egg Legion composed of former members of both communities, hiding out in the Mystic Ruins. After driving out the enemy, the two groups were convinced to share custody of the Black Emerald by Sally, who along with Sonic and Big the Cat were inducted into the Wolf Pack with their hands on the Emerald. Sally also voiced her concerns that the artifact resembled a Chaos Emerald, but Sonic was quick to dissuade her of the notion. (StH: #213, #214)
- The Black Emerald's role as Chaos' prison was taken from the Master Emerald in the video game Sonic Adventure. Because the Master Emerald had only been made recently in the comic continuity, it would not have been able to take the role and have the story make sense. As the universe has been reset by the Super Genesis Wave, Chaos' origin now matches that of the games, meaning the black Emerald is no longer in use.
- The Ancient Onyx and Black Emerald were confirmed to be the same on the Archie Sonic Blog.
- A Black Emerald was also featured in Fleetway's Sonic the Comic, where it served as the sustaining force of a dark zone known as the Shadow Dimension.