A Black Opal is a special type of gemstone used for creating memory orbs.
Like regular memory orbs they store and allow playback of memories. However, black opals are only used to record memories from recollectors.
They can be played back as normal by unicorns or by anyone wearing a recollector.
Descriptions and specifics of the various black opals can be found on the main memory orb page, along with the descriptions and specifics of regular memory orbs.
- A specific black opal is mention in Chapter 19 of Fallout: Equestria by Watcher. It is located in Tenpony Tower in the possession of Homage. Littlepip is sent to retrieve it, and manages to deliver it in Chapter 21, where it is revealed to belong to Spike who wants it because, "It was the last time Equestria's greatest mares, and my closest friends, were together. All of us. In the same place, at the same time. And happy."
- LittlePip finds another black opal in the Ministry of Morale hub in Fillydelphia.