Gradalith: Soil Lab is a geotechnical field companion for plotting grain-size distributions, calculating gradation coefficients, and organizing repeatable soil-classification work. KEY FEATURES - Sieve and hydrometer gradation workspace - Semi-log D10, D30, and D60 interpolation - Uniformity and curvature coefficients - Atterberg limits and plasticity cues - Transparent USCS decision support - Editable sample records plus CSV import - Scenario comparison and plotted curve - Local PDF analysis packet - Forty original offline soil-lab reference plates ONE-TIME AND PRIVATE - One paid download; no subscription or in-app purchase - No account, advertising, analytics, tracking, or developer-operated backend - Core tools and bundled reference material work offline - Work remains on device unless you deliberately import, share, or export through an Apple system interface Classifications are field and study aids, not a stamped geotechnical opinion. Follow project specifications, laboratory procedures, and qualified engineering review.