Rock identifier
What type of rock is this? Identify it, then see what it's worth
What type of rock is this, and is it worth anything? Upload a photo of the rock: the identifier names it, gives a rarity and value band, lists home tests to confirm it, and says whether to keep it or have it appraised.
What the rock report shows
The likely rock, mineral, geode or fossil, the look-alikes it was checked against, and how confident the match is.
How common a find it is, and a value band from comparable online listings.
Step-by-step checks to confirm a close call: streak, hardness, a magnet and a look at a fresh face.
One plain call, with the reason.
- Common: keep for fun
- Collect and store
- Get an expert appraisal
How to store or display it, and when an appraisal is worth paying for.
Your turn
Upload a photo of your rock
Daylight, the rock filling the frame, a coin beside it for scale. Trying the form is free: your first checks need no card and no account.
Photos
How to take a photo of a rock for identification
Clear photos give the best results. The camera on your phone is enough.
- Use daylightOutside in the shade or by a window: daylight shows the true color, the grains and the luster.
- Put a coin beside itA coin or a ruler next to the rock shows its size, which the value band needs.
- Step back to focusPhones blur at very close range. Move back until the surface is sharp, then crop.
- Show the most telling sideOne photo: if the rock has a broken or cut face, show that side, since the inside shows the grains and the crystals; otherwise the side with a crust or a rind.
- Leave the surface as it isDo not scrub off a crust or polish it first: the surface texture can be the clue that matters.
Method
How the rock identifier works
- 01
Upload a photo
One photo in daylight, the rock filling the frame, a coin beside it for scale, a broken face toward the camera if there is one.
- 02
It identifies the rock
The likely rocks, minerals, geodes or fossils, from color, luster, texture, grain and structure, with the look-alikes that are close.
- 03
It gives a rarity and value band
How common the find is and a band from comparable online listings, so you know a keepsake from a collector specimen.
- 04
It lists home tests
When two answers are close, it lists the test that tells them apart: for quartz and calcite, hardness.
- 05
You get a verdict
Keep it for fun, add it to a collection, or get an expert appraisal, with the reason and the next step.
Reference
Rock identifier basics: the three rock groups
A rock, also called a stone, is a natural solid mass of minerals or mineral-like matter such as volcanic glass. Geologists sort rocks into three groups by how they formed, and the identifier starts there.
- Igneous
Formed when magma cools in the crust, or lava cools on the surface or the seabed. Obsidian is an igneous rock: a volcanic glass formed when lava cools rapidly, with almost no crystals.
- Sedimentary
Formed from sediments, the weathered and deposited pieces of older rocks, pressed and cemented into rock.
- Metamorphic
Formed when existing rocks are changed by high pressure and temperature without melting much.
- Minerals
Rocks are made of one or more minerals. Quartz, one of the most common, is a defining part of granite and very common in sandstone.
Source: Wikipedia (Rock (geology); Obsidian; Quartz); USGS, as of
Reference
Home tests that confirm a rock or mineral
Each test narrows the list of rocks and minerals; two or three together say more than any one. The report says which ones settle your close call.
| Test | How | What it tells you |
|---|---|---|
| Streak | Drag a corner across the unglazed back of a porcelain tile | The color of the powder, which is steadier than the color of the surface |
| Hardness | Find what scratches it and what it scratches | Its place on the Mohs scale from 1 to 10: calcite is 3, quartz 7, diamond 10 |
| Magnet | Hold a cheap ceramic fridge magnet to it, not a rare-earth magnet | Most meteorites attract a cheap magnet; so do Earth rocks with magnetite, and slag. A rare-earth magnet pulls many ordinary rocks |
| A fresh face | Look at a broken surface | Grains, crystals and texture; obsidian and other glassy rocks break with a curved, shell-like fracture |
| Luster and texture | Look at the surface in daylight | Glassy, waxy, metallic or earthy: agate has a glossy, waxy look on a chipped spot |
- Test
- Streak
- Drag a corner across the unglazed back of a porcelain tile
- The color of the powder, which is steadier than the color of the surface
- Test
- Hardness
- Find what scratches it and what it scratches
- Its place on the Mohs scale from 1 to 10: calcite is 3, quartz 7, diamond 10
- Test
- Magnet
- Hold a cheap ceramic fridge magnet to it, not a rare-earth magnet
- Most meteorites attract a cheap magnet; so do Earth rocks with magnetite, and slag. A rare-earth magnet pulls many ordinary rocks
- Test
- A fresh face
- Look at a broken surface
- Grains, crystals and texture; obsidian and other glassy rocks break with a curved, shell-like fracture
- Test
- Luster and texture
- Look at the surface in daylight
- Glassy, waxy, metallic or earthy: agate has a glossy, waxy look on a chipped spot
Test a spare corner or a broken piece, never the best face of a specimen.
Source: Wikipedia (Streak (mineralogy); Mohs scale; Calcite; Quartz; Obsidian); Washington University in St. Louis; Minnesota DNR, as of
Reference
How to tell if a rock is a geode
A geode is a hollow, roughly round rock with mineral matter, often crystals, inside. These are the clues before you crack it.
- Shape
More or less round: geodes form in gas bubbles in volcanic rock, or in rounded cavities in sedimentary rock, as in the American Midwest.
- Where you find it
Geodes weather out of their bedrock and lie at the surface when they are made of resistant material such as quartz.
- What is inside
Quartz, clear, white or purple as amethyst, banded agate or chalcedony, calcite, celestite and other minerals.
- Bright colors
Some geodes on the market are dyed electric blue or pink, colors that do not form in nature.
Source: Wikipedia (Geode), as of
The result
What the rock identifier tells you after the name
The name is where the report starts, not where it stops.
- Rarity band
Whether it is a common rock, a nice specimen or something worth an expert look.
- Value band
A band from comparable online listings. When a rock is not worth selling, the report says so.
- Confirmation tests
The home tests that settle the close call, in the order to run them.
- Care and display
How to store, label and display it without lowering what it is worth.
Scope
What a rock identifier can and cannot tell from a photo
A photo can show
- The likely rock, mineral, geode or fossil
- The look-alikes it could be and the tests that tell them apart
- A rarity band and a value band from comparable listings
- Whether to keep it, collect it or have it appraised
Only an expert with it in hand can tell
- Confirm a meteorite: a lab test can
- A lab-grade classification of the rock
- Its exact weight, hardness or chemistry
- What a buyer will pay for it
A rock name is the first step. The identifier adds the rarity and value band, the home tests and a plain verdict, and says when a person should look at it in hand.
Next
After the rock identifier
The verdict points to one of these.
- 01
Keep it for fun
Label it with the name, the place and the date you found it, and keep it with your collection.
- 02
Show it to a gem and mineral club
Members of a local club look at rocks in hand, and many hobbyists are experts at identification.
- 03
Think it is a meteorite? Check the crust first
If it has no fusion crust, there is no reason to suspect a meteorite. Work through the checks of Washington University in St. Louis before you pay for a lab test.
Meteorite realities - 04
Check where you may collect
In the US, collecting rocks in national parks, national monuments and state parks is illegal (USGS); on private land, ask the owner first. Elsewhere, check the local rules.
A rock identifier gives a first answer, not the last one
The USGS says rocks and minerals are extremely difficult to identify from photographs and must be examined in person. The identifier gives a first answer with its confidence and the home tests that settle it. For a valuable specimen, take it to a state geological survey, a natural science museum, a university geology department or a local gem and mineral club.
Limits
What a rock identifier cannot promise
Value bands are estimates from comparable listings, not an offer or an appraisal. Rocks are hard to identify from photographs: confirm with the home tests or an expert. A photo cannot confirm a meteorite or a rare fossil: a lab or a museum can. We do not buy rocks.
FAQ
Rock identifier: frequently asked questions
How do I identify what type of rock this is from a picture?
Upload a clear daylight photo with a coin for scale. The identifier names the likely rock or mineral, shows the look-alikes, and lists the home tests that settle a close call.
What is this stone? Can you tell from one photo?
As a first answer, not a final one. The USGS warns that rocks are extremely difficult to identify from photographs, so the report gives its confidence and the tests to confirm it, and says when to take the stone to an expert.
Can I use a rock identifier online free without signing up?
Trying the form is free: your first checks need no card and no account, and there is no app to install.
Can Google Lens or other apps identify rocks and minerals?
They can suggest a name. For meteorites, the meteorite site of Washington University in St. Louis says such apps are nearly always wrong when they suggest a meteorite. This identifier pairs a name with home tests and a confidence, so you can check the answer yourself.
How can I tell if a rock is valuable or just a common specimen?
The report gives a rarity band and a value band from comparable listings, weighing the mineral, its crystals, its size and condition, and says plainly when it is a keepsake.
Is it an agate? What does the outside of an agate look like?
A raw agate rarely shows its bands. Look for a pitted surface, a waxy look on a chipped spot and a glow when light passes through. The crystal identifier covers agate in detail.
Is it a meteorite?
Start with the crust: almost every meteorite has a thin fusion crust, black on most, and most attract a cheap magnet. Many Earth rocks attract a magnet too, so only a lab test confirms one.
Quartz or calcite?
Hardness tells them apart: quartz is 7 on the Mohs scale and calcite 3, so quartz scratches calcite and calcite cannot scratch quartz. The report lists that test when the two are close.
Is it petrified wood?
Petrified wood is fossil wood whose cells were replaced by minerals, mostly silica such as chalcedony or quartz. The identifier reads the texture the wood left in the stone.
Should I cut, polish or clean it first?
Not before you know what it is: cutting, polishing or acid can lower its value, and a crust may be the clue that matters.
What should I do if the identification looks wrong?
Run the home tests the report lists, and try again with a photo of a broken face, if it has one. If they disagree with the name, trust the tests and ask a local club.
Why won't my close-up rock photos focus?
Phone cameras blur when they are too close. Step back until the surface is sharp and crop the photo afterwards.
Are rock identifier apps worth it, or is there a better way?
An identifier is a fast first answer. A geological survey, a museum, a university geology department or a gem and mineral club can look at the rock in hand, and the report says when that is the better way.
Can someone tell me what this is and how much it's worth?
The report gives a first answer to both from one photo: the name with its confidence and a value band from comparable listings, and it says plainly when a rock is not worth selling.
Found something on a hike or a beach?
Leave it as it is, note where you found it, and upload a photo to see what type of rock it is.