Petralux

Petralux is an offline reference: minerals, gemstones and how to tell them apart. • Minerals — 17 species • Gemstones — 14 gems • Identification — 13 methods • Glossary — 20 terms • Quiz — questions built from the same entries • Favorites — keep the entries you return to Every entry has a short summary line and a few paragraphs of description. Search works inside each section. Nothing is downloaded: all 44 entries ship inside the app and work without a connection. Petralux covers 17 rock-forming and common minerals, 14 gemstones and 13 identification methods used by collectors and field geologists. Each entry gives the chemical formula, Mohs hardness and crystal system, describes the distinguishing features, explains where the material is found and how it is used, and closes with one memorable fact. A glossary explains the vocabulary of streak, cleavage, lustre and specific gravity. Descriptions were compiled from standard mineralogy and gemmology references and checked against published values for hardness, density and composition. The app works fully offline. It is a reference only, not a laboratory or field kit: tests such as scratching, acid and ultraviolet light should be carried out with proper care, and valuable stones should be identified by a qualified gemmologist.