Field assessment
Upload a rock photo and get a cautious, geology-focused estimate of whether it may contain a cavity or crystal growth.
Important limitation
A surface photo cannot prove what is inside a stone. The app provides an educational field estimate, not a geological certainty.
Best results come from one clear photo of the whole specimen in natural light, ideally with visible texture, rind, fractures, and scale.
Tip: include a coin, ruler, or hand only if it does not cover diagnostic features.
Read the likelihood score together with the evidence, confidence rating, and limitations.
No analysis yet
Upload one specimen photo and run the assessment to see a geology-focused estimate.
Many geodes begin as cavities in volcanic or sedimentary settings that later receive silica-rich fluids, depositing chalcedony, quartz, calcite, or amethyst inward from the walls.
Rounded concretions, ironstone nodules, weathered basalt, and ordinary fracture-filled rocks can resemble geodes from the outside while lacking a crystal-lined cavity.
Compare mass to size, inspect fresh chips for silica banding, gently tap for resonance, and document locality. Use destructive cutting only when safety and legal context are clear.
Quartz and chalcedony are most common, but calcite, amethyst, celestine, barite, and other minerals can line cavities depending on chemistry and host environment.
