#clusters warning

Content Warning: images of clusters and groups of small holes (may trigger trypophobia)

omg it’s hard to explain in text form but basically regular precious opals are made up of silicon dioxide spheres that are packed in planes, and this structure is part of what gives opals their optical properties

inverse opals are synthesized by replicating this same structure using a polymer like polymethylmethacrylate (PMMA) and then depositing silicon dioxide into the negative space between the spheres. the PMMA is then removed and what you’re left is is the “inverse” or “negative” of the structure of a regular opal.

what’s EXTREMELY cool about inverse opals is that they look almost identical to regular opals!!!! they exhibit a similar opalescent property (see below)