Lithify: Geology Field Guide
Rock & Mineral Field Guide
$2.99 · Designed for iPad. Not verified for macOS.
New in 2.0: look-alikes with side-by-side compare, collection insights, CSV/PDF export and backups, plus a Specimen of the Day widget. Still one purchase, fully offline.
Lithify is a serious, offline field guide for rockhounds, geology students, prospectors and hikers. It pairs a genuine identification engine with a richly illustrated reference library of 101 rocks and minerals — all on your device, with no account, no subscription, and no photos leaving your phone.
Most rock-ID apps upload your pictures to a cloud service and hide the answer behind a subscription. Lithify does not pretend an AI can name a rock from one picture: it teaches you to identify a specimen the way a geologist does — by its diagnostic properties — and shows its work every step of the way.
NEW IN 2.0
• Look-alikes & Compare — every entry lists the specimens it is most easily confused with. Compare any two side by side and Lithify ranks the field tests that tell them apart: magnet, acid, scratch, streak, heft, luster and cleavage.
• Collection Insights — your life list against the guide, finds per month, top localities, what you collect, and a measurement check that flags hardness or specific-gravity readings outside the guide's range.
• Export & backup — share your log as a spreadsheet (CSV) or a printable PDF field log, and back up or restore the whole collection, photos included, as a single file.
• Widgets & shortcuts — a Specimen of the Day widget for the Home Screen and Lock Screen, a Control Center control that opens the key (iOS 18), and Siri shortcuts to identify a rock or log a find.
• Guide badges show what you already own, with a "Not yet collected" filter.
IDENTIFY, HONESTLY
• Dichotomous Key — an adaptive question-and-answer key that starts from luster, hardness and streak and narrows the field with each answer, showing the live candidate count.
• Property Matcher — enter whatever you observed (hardness band, streak color, cleavage, magnetism, acid reaction, color) and get a ranked shortlist scored by how well each specimen agrees. Partial information still helps.
• Photo Color Assist — sample a photo's dominant colors on-device to suggest color-consistent candidates. An aid, never an automatic verdict.
A REAL REFERENCE LIBRARY
• 69 minerals and 32 rocks (igneous, sedimentary, metamorphic), each with a curated photo gallery.
• Factual structured properties: Mohs hardness, streak, luster, cleavage, fracture, specific gravity, crystal system, chemical formula, diaphaneity, tenacity, magnetism and acid reaction.
• Classification by mineral group plus Dana and Strunz numbers.
• Formation environments, notable localities, common uses, and field-identification tips for every entry.
• Search and filter by type, rock class, hardness band, color and collection status.
FIELD TOOLS
• Mohs Scale — the ten index minerals, common field-test tools (fingernail, copper coin, steel, glass), and how to run a proper scratch test.
• Specific Gravity Calculator — compute SG by the hydrostatic (Archimedes) method or mass ÷ volume, then match your result against minerals of that density.
• Test Reference — how to read streak, luster, cleavage versus fracture, and the acid test.
YOUR COLLECTION
• Log the specimens you find with a photo, a linked field-guide entry, the locality, the date, and optional coordinates.
• Record your own hardness and specific-gravity measurements and see how they compare with the guide.
• Search your log, export it, and keep file backups. Everything is stored locally on your device.
PRIVATE AND OFFLINE BY DESIGN
• Works everywhere — the quarry, the trail, the plane — with no signal.
• No account, no sign-in, no subscription, no in-app purchases.
• No analytics, no tracking. Your photos and collection never leave your device unless you export them.
Specimen photographs are sourced from Wikimedia Commons under public-domain, CC0, CC-BY and CC-BY-SA licenses, with full per-image attribution inside the app.
Buy it once. Own it forever. Take it anywhere.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Lithify 2.0 is a major upgrade, included free for everyone who owns the app.
• Look-alikes & Compare: see which specimens are easily confused and the field tests that tell them apart.
• Collection Insights: life list, finds per month, top localities and a measurement check against the guide.
• Export & backup: CSV spreadsheet, PDF field log, and full backup/restore with photos.
• Specimen of the Day widget for the Home and Lock Screen, a Control Center control, and Siri shortcuts.
• Guide badges and a "Not yet collected" filter.
• Fixed: your collection log now reloads reliably after the app restarts (older saved logs are read too).
• Fixed: editing an entry shows its field-guide match and no longer leaves old photos behind.
• Fixed: specific-gravity entry accepts comma decimals; the streak tile shows the full streak color.
• Better contrast, larger-text layouts and iPad reading widths.
The developer, Robert Corbin, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Robert Corbin
- Size
- 123.8 MB
- Category
- Reference
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Robert Corbin
