Common minerals
49 minerals chosen because they are the ones amateurs actually find, not because they are the ones textbooks list first. Each page gives the tests that confirm it and the specific reason it gets mistaken for something else.
Native elements
Minerals made of a single element — gold, copper, sulfur, graphite.
Native gold is soft, heavy, and unreactive.
Graphite is pure carbon arranged in sheets that slide over one another, which is why it feels greasy and writes on paper.
Native sulfur is the bright yellow crust around volcanic vents and hot springs, and it also occurs in salt-dome cap rock.
Native copper is one of the very few metals that occurs naturally in usable metallic form, which is why it was the first metal humans worked.
Sulfides
Metallic ore minerals. Heavy, often brassy or gray, and the source of most false gold reports.
Pyrite is the mineral behind essentially every 'I think I found gold' photograph.
Chalcopyrite is the world's most important copper ore and the second most common cause of false gold reports.
Galena is lead sulfide, and it behaves exactly the way a lead mineral should: soft, extremely heavy, and bright metallic gray.
Sphalerite is the main ore of zinc and one of the more confusing common minerals, because its colour ranges from near-transparent yellow to opaque black.
Molybdenite is the primary ore of molybdenum and looks almost exactly like graphite.
Marcasite has the same chemistry as pyrite but a different crystal structure, and it is the less stable of the two.
Stibnite is the main ore of antimony and one of the most striking metallic minerals a collector can own — long steel-grey blades that look almost manufactured.
Oxides
Metal-plus-oxygen minerals, including the iron ores and corundum.
Magnetite is the black, strongly magnetic iron oxide that makes up most of the 'black sand' left in the bottom of a gold pan.
Hematite is iron oxide and the reason so much of the world's soil and sandstone is red.
Chromite is the only ore of chromium and looks much like magnetite.
Corundum is aluminium oxide and the second-hardest natural mineral.
Cassiterite is the world's only significant ore of tin and the reason Cornwall and the Erzgebirge mattered in European history.
Hydroxides
Weathering products — the brown rust of the mineral world.
Halides
Salt-family minerals. Soft, often colourful, and sometimes water-soluble.
Carbonates
The acid-test family. Most fizz in vinegar.
Calcite is the mineral of limestone, marble, cave formations, and most seashells.
Dolomite is calcite's magnesium-bearing cousin and is almost indistinguishable by eye.
Malachite is the green weathering product of copper ore and one of the most visually distinctive minerals there is.
Azurite is malachite's blue counterpart, formed in the same oxidised copper zones.
Rhodochrosite is manganese carbonate and one of the most recognisable pink minerals.
Sulfates
Soft, often pale, and sometimes surprisingly heavy.
Phosphates
Includes apatite and turquoise.
Silicates
The largest group by far — most of the Earth's crust is silicate.
Quartz is the most abundant mineral in the Earth's crust and the one every rockhound learns first.
Chalcedony is quartz built from crystals too small to see, which gives it a waxy lustre and a tough, even texture.
Feldspar is the most abundant mineral group in the Earth's crust — the pink and white grains that make up most of a granite.
Muscovite is the silvery mica in granite and schist, and the elastic-sheet test is unmistakable.
Biotite is the black mica in granite, and it accounts for most of the dark specks in a light-coloured igneous rock.
Chlorite gives greenschist its colour and its name.
Talc is the bottom of the Mohs scale and the substance of talcum powder.
Serpentine forms when water alters magnesium-rich igneous rock, and it is very often sold as jade.
Garnet is the classic red crystal of metamorphic schist, and its rounded many-sided crystals embedded in mica are one of the most satisfying things a beginner can find.
Topaz is a pegmatite mineral, hard enough to scratch quartz and heavy enough to feel wrong in the hand.
Beryl grows in pegmatites, sometimes in crystals metres long.
Tourmaline is instantly recognisable once you have seen the striated, triangular prisms.
Hornblende is the most common dark mineral in intermediate igneous rocks such as diorite and andesite.
Augite is the dominant dark mineral in basalt and gabbro.
Olivine is the main mineral of the Earth's upper mantle, and it arrives at the surface as green nodules carried up in basalt.
Epidote forms when other minerals are altered by hot fluids, and its yellow-green colour is one of the more memorable in mineralogy.
Jade is two different minerals sharing one name and one property: an interlocking fibrous structure that makes them almost unbreakable.
Kyanite is the mineral that breaks the Mohs scale, because its hardness depends on the direction you test.
Sodalite is the affordable blue ornamental stone, widely sold in place of lapis lazuli.
Mineraloids
Not true minerals: no crystal structure. Obsidian and opal.