Spinel crystal in dolomite marble, Burma

Agate from Reichweiler, Germany

Fire opal, Mexico

Stress fissure («sun spangle») in baltic amber

Agate from Anzi, Maroc

Inclusions of rock crystal and rutile needles in quartz, Brazil, polarised light

Structure in a healing fissure in topaz from Brazil

Inclusions of hematite in feldspar (sunstone), India

Epigenetic inclusion (probanly melanterite) in quartz, Brazil, parallel polarisers