Opal

Its internal structure causes it to reflect a rainbow of light.
Overview
Opal is a mineral that can be found in the 

Opal also has two practical uses beyond being sold or kept as part of a collection. It is used in the spool of the 


- Source: Frozen Geode, Omni Geode
- Tailoring use: Shirt
- Dyeing use: blue dye
Official description
Its internal structure causes it to reflect a rainbow of light.