Mineral identification chart you narrow down with home tests

Tell the chart what your stone does with a nail, a tile, a magnet and vinegar, and it narrows 49 common minerals and rocks. Free and printable.

Updated 29 October 2026Tested in Chrome on a phone-sized screen and a laptop, October 2026

Name	Colour	Streak	Hardness	Shine	Magnet	Vinegar	Breaks	Weight	The giveaway
Quartzmineral	White, grey, pink, purple, yellow, brown, black	White or none	7	Glassy, greasy	No	No	Shell-like	Average	Scratches glass easily and breaks with curved, shell-like edges, never flat faces.
Chalcedonymineral	White, grey, blue, brown, red, orange, yellow, green, black	White or none	6.5 to 7	Greasy, dull	No	No	Shell-like	Average	Quartz in grains too fine to see, with a waxy shine. Agate shows bands, jasper is opaque red, brown or yellow.
Potassium feldsparmineral	White, pink, orange, grey, yellow, green	White or none	6 to 6.5	Glassy, pearly	No	No	Flat faces, rough	Average	The pink or cream blocky crystals in granite. Two flat breaking faces at right angles, and too hard for a steel nail.
Plagioclase feldsparmineral	White, grey, blue, green, brown	White or none	6 to 6.5	Glassy, pearly	No	No	Flat faces, rough	Average	Like potassium feldspar but white to grey, often with fine parallel lines on its flat faces. Labradorite flashes blue.
Calcitemineral	White, grey, yellow, green, orange, brown, pink, blue	White or none	3	Glassy, pearly	No	Fizzes	Slanted blocks	Average	Fizzes in vinegar, a steel nail scratches it, and it breaks into slanted blocks. Clear pieces show a doubled image.
Dolomitemineral	White, yellow, brown, pink, grey	White or none	3.5 to 4	Glassy, pearly	No	Weak or none	Slanted blocks	Average	Looks like calcite but barely reacts to vinegar unless you scratch some into powder first. Crystals often have curved faces.
Gypsummineral	White, grey, yellow, brown, pink, red	White or none	1.5 to 2	Glassy, pearly, silky	No	No	Thin sheets, fibres	Light	So soft your fingernail leaves a mark. Clear sheets bend without springing back.
Halitemineral	White, grey, pink, orange, red, blue, purple, yellow	White or none	2 to 2.5	Glassy	No	No	Cubes	Light	Breaks into cubes and dissolves in a glass of water.
Fluoritemineral	White, purple, blue, green, yellow, orange, pink, brown, black	White or none	4	Glassy	No	No	Flat faces	Average	Often cubes, but the corners break off as flat triangles. A steel nail scratches it, copper doesn't.
Barytemineral	White, grey, yellow, brown, pink, blue	White or none	3 to 3.5	Glassy, pearly	No	No	Flat faces	Heavy	Pale and glassy like calcite, but noticeably heavy for its size and no fizz.
Muscovite micamineral	White, grey, brown, green, yellow, pink	White or none	2.5 to 3	Glassy, pearly, silky	No	No	Thin sheets	Average	Peels into clear, paper-thin sheets that spring back when bent.
Biotite micamineral	Black, brown, green	White or none	2.5 to 3	Glassy, pearly, metallic	No	No	Thin sheets	Average	Black or brown flakes that peel into thin sheets. The dark sparkles in granite.
Talcmineral	White, green, brown, grey	White or none	1	Pearly, greasy, dull	No	No	Thin sheets, rough	Average	Feels soapy, and a fingernail scratches it with no effort. The softest mineral on the Mohs scale.
Chloritemineral	Green	White or none, green	2 to 2.5	Pearly, greasy, dull	No	No	Thin sheets	Average	Green flakes like a soft mica, but they bend and stay bent.
Serpentinemineral	Green, white, yellow	White or none	2.5 to 3.5	Greasy, silky, dull	No	No	Shell-like, fibres, rough	Average	Mottled green with a waxy, soapy feel. Some kinds are fibrous asbestos, so don't scrape or crush fibres.
Graphitemineral	Black, silver-grey	Grey to black	1 to 2	Metallic, dull	No	No	Thin sheets	Light	Writes on paper like a pencil and feels greasy. Light for a metallic-looking mineral.
Pyritemineral	Brassy gold	Grey to black	6 to 6.5	Metallic	No	No	Shell-like, rough	Heavy	Pale brassy cubes with a greenish-black streak. Too hard for a steel nail, while real gold is soft and leaves a gold streak.
Chalcopyritemineral	Brassy gold, blue, purple	Grey to black	3.5 to 4	Metallic	No	No	Rough	Heavy	Deeper yellow than pyrite, often with a rainbow tarnish, and a steel nail scratches it.
Galenamineral	Silver-grey	Grey to black	2.5 to 2.75	Metallic	No	No	Cubes	Heavy	Bright silver cubes that are very heavy for their size. Wash your hands after handling it.
Sphaleritemineral	Brown, yellow, black, red, green, white	Yellow-brown, white or none	3.5 to 4	Greasy, glassy	No	No	Flat faces	Heavy	Resin-like brown or black with many flat shiny faces, and a pale yellow-brown or white streak.
Hematitemineral	Silver-grey, black, red, brown	Red-brown	5 to 6	Metallic, dull	No	No	Rough	Heavy	Red-brown streak even when the stone itself is shiny black or grey. Heavy.
Magnetitemineral	Black	Grey to black	5.5 to 6.5	Metallic, dull	Yes	No	Rough	Heavy	A fridge magnet sticks to it. Black streak and heavy.
Goethitemineral	Brown, yellow, black, orange	Yellow-brown	5 to 5.5	Metallic, dull, silky	No	No	Rough, fibres	Heavy	Rusty brown with a yellow-brown streak. Earthy limonite crusts are softer than the crystals.
Pyrrhotitemineral	Brassy gold, brown	Grey to black	3.5 to 4.5	Metallic	Weak	No	Rough	Heavy	Bronze, tarnishes fast, and pulls weakly towards a strong magnet.
Malachitemineral	Green	Green	3.5 to 4	Glassy, silky, dull	No	Weak or none	Rough, fibres	Average, heavy	Bright green, often in bands, with a pale green streak. A copper mineral.
Azuritemineral	Blue	Blue	3.5 to 4	Glassy	No	Weak or none	Rough, shell-like	Heavy	Deep blue with a pale blue streak, often found with malachite.
Garnetmineral	Red, brown, black, purple, orange	White or none	6.5 to 7.5	Glassy, greasy	No	No	Shell-like, rough	Average, heavy	Dark red ball-shaped crystals with many faces, often sitting in schist. Scratches glass.
Olivinemineral	Green, yellow, brown	White or none	6.5 to 7	Glassy	No	No	Shell-like	Average	Bottle-green glassy grains, often in lumps inside dark basalt.
Hornblendemineral	Black, green, brown	White or none	5 to 6	Glassy, pearly	No	No	Flat faces	Average	Black, long crystals with two flat breaking faces at a slant (about 56 and 124 degrees).
Augitemineral	Black, brown, green	Green, white or none	5.5 to 6	Glassy, dull	No	No	Flat faces	Average, heavy	Like hornblende, but stubby, and its two flat faces meet at nearly a right angle.
Tourmalinemineral	Black, brown	White or none	7	Glassy, greasy	No	No	Shell-like, rough	Average	Black, long crystals with fine grooves along their length and a rounded triangle shape end-on. Common in granite.
Apatitemineral	Green, blue, purple, pink, yellow, brown, white	White or none	5	Glassy, greasy	No	No	Shell-like, rough	Average	Six-sided crystals right on the line of a steel nail: the nail scratches it only just.
Epidotemineral	Green, yellow, black	White or none	6 to 7	Glassy, pearly	No	No	Flat faces, rough	Average	Pistachio green, often as veins or crusts in darker rock.
Graniterock	Pink, grey, white	Not useful	6 to 7	Glassy	No	No	Rough	Average	Speckled with crystals big enough to see: glassy grey quartz, pink or white feldspar and black mica.
Basaltrock	Black, grey	Not useful	5.5 to 6.5	Dull	Weak	No	Rough	Average	Dark and fine-grained, sometimes with gas holes or green olivine lumps. Some basalt pulls weakly on a magnet.
Obsidianrock	Black, brown, red	Not useful	5 to 5.5	Glassy	No	No	Shell-like	Average	Natural black glass with razor-sharp curved edges. Thin edges let light through.
Pumicerock	White, grey	Not useful	Varies	Dull	No	No	Rough	Light	Full of tiny holes, like frozen foam. It floats in water.
Sandstonerock	Yellow, brown, red, grey, white	Not useful	Varies	Dull	No	Weak or none	Rough, flat slabs	Average	Gritty like sandpaper, with sand grains you can see. Grains may rub off on your fingers.
Mudstone and shalerock	Grey, black, brown, red	Not useful	Varies	Dull	No	Weak or none	Flat slabs, rough	Average	Smooth with no grains you can see. Shale splits into thin layers.
Limestonerock	Grey, white, yellow, brown	White or none	3 to 4	Dull	No	Fizzes	Rough	Average	Fizzes in vinegar and often holds fossil shells.
Chalkrock	White	White or none	1 to 3	Dull	No	Fizzes	Rough	Light, average	Soft white limestone that marks your fingers and fizzes in vinegar.
Flintrock	Black, grey, brown	Not useful	6.5 to 7	Glassy, greasy, dull	No	No	Shell-like	Average	Dark grey or black inside a white crust, with sharp, curved edges where it breaks. It forms in chalk.
Marblerock	White, grey, pink, green	White or none	3 to 4	Glassy	No	Fizzes	Rough	Average	Sugary sparkling crystals that fizz in vinegar. A steel nail scratches it.
Slaterock	Grey, black, purple, green	Not useful	Varies	Dull	No	No	Flat slabs	Average	Splits into thin, flat, smooth sheets.
Quartziterock	White, grey, pink	Not useful	7	Glassy	No	No	Rough, shell-like	Average	Looks like sandstone, but breaks through its grains, not around them, and scratches glass.
Schistrock	Grey, silver-grey, green, brown	Not useful	Varies	Pearly, glassy	No	No	Flat slabs	Average	Glittery with mica flakes lined up in wavy layers. Often has garnets in it.
Gneissrock	Grey, pink, white, black	Not useful	6 to 7	Glassy	No	No	Rough, flat slabs	Average	Granite-like crystals sorted into light and dark stripes.
Conglomeraterock	Brown, grey, red, yellow, white	Not useful	Varies	Dull	No	Weak or none	Rough	Average	Rounded pebbles cemented together in a sandy rock.
Coalrock	Black	Grey to black	Varies	Dull, glassy, metallic	No	No	Rough, shell-like	Light	Black, light for its size, and leaves a black or brown-black streak. Dirties your fingers.

What you need for the tests

The unglazed back of a white bathroom tile, for the streak.
A steel nail and a glass jar or bottle, for hardness.
A copper coin. In the UK, check it first (see below).
A fridge magnet. Don't use a strong neodymium magnet, which pulls on plenty of ordinary rocks.
White vinegar and a dropper or a straw.
A plain pebble about the size of your find, to compare the weight.

The coin needs care. The Royal Mint says UK 1p and 2p coins have been copper-plated steel since September 1992, and a steel coin scratches like a nail, not like copper. Older bronze ones look identical, but a magnet won't pick them up. So hold your coppers to a magnet and use one that doesn't stick. A bit of copper pipe or thick copper wire works too.

Do the tests in this order

Find or make a fresh surface. Weathered outsides hide the colour and the shine, so chip a corner if you can.
Rub the stone hard across the back of the tile and look at the powder line, not the stone.
Try to scratch it with your fingernail, then the copper, then the nail. Then see whether it scratches the glass. Wipe the mark with a wet finger, because soft powder can look like a scratch.
Hold it near the magnet on a thread and watch for a pull.
Put one drop of vinegar on a fresh surface and watch for a minute. If nothing happens, scratch a little powder and try the drop on that.
Look at a broken edge. Thin sheets, cubes, slanted blocks and curved shell-like edges each point to a different group.
Weigh it in your hand against the pebble.

Streak comes before scratching because the scratch test leaves marks. Vinegar comes late because the fizz is acid eating into the stone, so rinse it with water afterwards.

Which tests narrow it most

We counted how far each test cuts the chart's 49 entries, on average over every stone in it. How it breaks did the most. It left about 16. Colour left about 19, but colour is also the test most likely to mislead. Quartz alone comes colourless, pink, purple, yellow, brown or black, according to the Handbook of Mineralogy, depending on what's trapped inside it.

Scratch and weight each left about 26, and streak about 28. Streak looks weak only because 23 of the 33 minerals leave a white streak, and rocks rarely give a useful one. When a streak does have colour, it's one of the strongest clues you'll get. Hematite leaves a red-brown streak even when the stone itself is shiny black.

The magnet left about 46, because so few things here react. But when a fridge magnet does pull, the list drops to 3.

Reading the scratch test

The tools have rough Mohs hardness values. A Texas A&M International University lab guide puts a fingernail at 2.5 and a steel nail at about 5, with most pocket knives at 5 to 5.5. Western University's guide puts copper at 3 and a glass plate at 5.5. Sources disagree by half a step, and so do real nails and coins.

So the chart lets its scratch bands overlap a little. Calcite is hardness 3, right on the copper line, and it stays in the list whether you say the coin scratched it or not. If one of your answers was wrong, the chart also shows near misses: stones that fit everything except one test, with a note saying which.

Print the chart for a class

Print the chart prints all 49 rows, in landscape. Each row has every property and the giveaway, and the rest of the page stays off the paper. Faded rows print at full strength. Minerals are taken from the Handbook of Mineralogy, published by the Mineralogical Society of America, and rocks from the Natural History Museum's guide to UK rocks.

Rocks behave less neatly than minerals, because a rock is a mix of minerals. The chart gives a rock a hardness only when one mineral decides it, like the calcite in limestone. For the rest it says "Varies", and that test never rules the rock out.

What the chart can't tell you

It can't tell you whether a gem is real or what anything is worth. A jeweller or a gem lab can.

It can't confirm a meteorite either. The meteorite pages run at Washington University in St. Louis say about 95% of meteorites attract a cheap magnet, but so do rocks with magnetite in them and industrial slag. Iron-oxide lumps are the most common "meteorwrong" they're sent, and they suggest a streak test. On this chart, a red-brown or yellow-brown streak points to hematite or goethite. If a heavy, magnetic find gets past that, take it to a museum or a university geology department.

Fossils, shells, sea glass and man-made materials like brick and concrete aren't in the chart.

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