Stonetable

火成岩IgneousCooling history written in grain size: coarse where the melt ponded underground, glassy where it was chilled at the surface.6 sheets live

沉积岩SedimentaryGrains, cements and bedding. These are the rocks that record water, wind, life and time without metamorphosing any of it away.4 sheets live

变质岩MetamorphicThe same protolith at different grades: shale becomes slate, then phyllite, then schist, then gneiss, and each step is readable.4 sheets live

矿物MineralsIdentified by properties rather than names: hardness, cleavage, streak, lustre, acid reaction, magnetism, density.5 sheets live

Igneous rocks — solidified from melt

Igneous · 6 sheets published
Sheet	Name	Formula	Mohs
ST-001 Igneous	Granite花岗岩 Granite is the rock most people name correctly and describe least accurately. It is the coarse, light-toned intrusive rock built from quartz, alkali feldspar and a little mica — but the iden Hand specimen	Quartz SiO₂ + alkali feldspar (KAlSi₃O₈) + plagioclase + mica	6–7 aggregate (quartz-controlled)
ST-002 Igneous	Granodiorite花岗闪长岩 Granodiorite looks like a slightly dirty granite and is routinely filed as one. It is the most abundant plutonic rock in the continental crust, and the difference from true granite is not co Hand specimen	Quartz SiO₂ + plagioclase (NaAlSi₃O₈–CaAl₂Si₂O₈) + hornblende + biotite	6–7 aggregate
ST-003 Igneous	Basalt玄武岩 Basalt is the most common rock on the planet's surface and one of the hardest to describe from a single specimen, because almost everything diagnostic is too small to see. It is dark, fine-g Hand specimen	Plagioclase (Ca-rich) + clinopyroxene + olivine; SiO₂ about 45–52 wt%	5–6 aggregate (pyroxene-controlled)
ST-004 Igneous	Obsidian黑曜岩 Obsidian is the geological exception that proves the rule about igneous rocks: it is an igneous rock that contains no minerals in the strict sense, because it cooled so fast that its atoms n Hand specimen	Amorphous SiO₂-rich glass, roughly 70–77 wt% SiO₂, with 1–3 wt% water	5–5.5 (glass hardness)
ST-005 Igneous	Pumice浮岩 Pumice is the only common rock that reliably floats on water, and the reason is simple arithmetic: 60 to 85 percent of its volume is gas. It is a volcanic glass foam, quenched so violently b Hand specimen	Amorphous SiO₂-rich glass with 60–85 vol% vesicles; SiO₂ about 65–75 wt%	6 (glass, but collapses under point load)
ST-007 Igneous	Granite vs granodiorite花岗岩与花岗闪长岩对照 These two rocks sit next to each other in every classification chart and are routinely confused in the field, because they share their texture, their grain size, most of their minerals and t Comparison sheet	Difference is in the feldspar budget: alkali feldspar-dominant versus plagioclase-dominant	Both 6–7 aggregate; hardness does not separate them

Sedimentary rocks — deposited, then lithified

Sedimentary · 4 sheets published
Sheet	Name	Formula	Mohs
ST-008 Sedimentary	Sandstone砂岩 Sandstone is a photograph of a current. Every grain in it was moved by water or wind, and three measurements taken in the field — grain size, sorting and roundness — tell you how far it trav Hand specimen	Quartz grains (SiO₂) with a cement of silica, calcite, iron oxide or clay	6–7 for quartz grains; the rock's resistance is set by the cement
ST-009 Sedimentary	Limestone石灰岩 Limestone is the easiest of the common rocks to identify and the hardest to identify well, because one drop of acid answers the first question and leaves every interesting question untouched Hand specimen	CaCO₃, mostly as calcite, with variable clay, silica and magnesium	3 (calcite controls everything)
ST-010 Sedimentary	Shale页岩 Shale accounts for more than half of all sedimentary rock in the record and gets almost none of the attention. It is a mudrock — clay minerals, fine silt and often a few percent of organic c Hand specimen	Clay minerals + quartz silt + organic carbon; illite and kaolinite dominate	2–3 (clay minerals; the rock is soft and scratches with a fingernail in places)
ST-011 Sedimentary	Chert燧石 Chert is a sedimentary rock made of quartz so fine that no individual crystal can be seen at any useful magnification, and that fineness gives it two properties that changed human history: i Hand specimen	SiO₂ as microcrystalline quartz and chalcedony, with minor opal	7 (quartz hardness throughout)

Metamorphic rocks — recrystallised under pressure and heat

Metamorphic · 4 sheets published
Sheet	Name	Formula	Mohs
ST-015 Metamorphic	Marble大理岩 Marble is limestone that has been cooked. Given enough heat and pressure, calcite grains recrystallise into a dense interlocking mosaic, the fossils and bedding are destroyed, and the rock b Hand specimen	Recrystallised CaCO₃; dolomitic marble is CaMg(CO₃)₂	3–4 (calcite marble), 3.5–4 (dolomitic marble)
ST-016 Metamorphic	Slate板岩 Slate is the grade of metamorphosed mud that industry was built on: it splits into thin waterproof sheets, which made it the roofing material of eighteenth- and nineteenth-century Europe and Hand specimen	Fine-grained white mica (sericite), chlorite and quartz after a shale protolith	3–4; the rock is soft but splits into very tough sheets
ST-017 Metamorphic	Schist片岩 Schist is the middle grade of regional metamorphism — hot enough, roughly 400 to 600 degrees Celsius, for mica to grow into flakes you can see and for new minerals to crystallise that carry Hand specimen	Variable: muscovite, biotite, chlorite, quartz, feldspar, garnet, staurolite, kyanite	Variable with mineralogy; 4–7 depending on quartz and garnet content
ST-018 Metamorphic	Gneiss片麻岩 Gneiss is the highest grade of common metamorphic rock, formed at temperatures above about 600 degrees Celsius and often at pressures corresponding to 20 to 30 kilometres of burial. Its defi Hand specimen	Quartz + feldspar + biotite or hornblende, segregated into light and dark bands	6–7 (dominated by quartz and feldspar)

Minerals — the single substances rocks are made of

Minerals · 5 sheets published
Sheet	Name	Formula	Mohs
ST-021 Minerals	Quartz石英 Quartz is the most useful single mineral in field identification, not because it is interesting to look at but because of what its hardness does to everything else. At 7 on Mohs' scale it si Mineral species	SiO₂	7
ST-022 Minerals	Orthoclase (alkali feldspar)正长石（碱性长石） Orthoclase is the alkali feldspar — potassium aluminium silicate — and it is the mineral responsible for the pink colour of most granite. Its name means "right-angle fracture", referring to Mineral species	KAlSi₃O₈	6
ST-023 Minerals	Calcite方解石 Calcite is the reference mineral for hardness 3, the fizz in an acid test, and above all for cleavage — three perfect directions that break a crystal into rhombs and make calcite one of the Mineral species	CaCO₃	3
ST-024 Minerals	Pyrite黄铁矿 Pyrite is the mineral that built the phrase "fool's gold", and the deception works because pyrite genuinely looks metallic and golden in a stream bed. It is iron disulfide, the most common s Mineral species	FeS₂	6–6.5
ST-025 Minerals	Halite (rock salt)石盐（岩盐） Halite is sodium chloride — table salt — and it is the one common mineral for which taste is a legitimate field test. It forms by evaporation, it cleaves into perfect cubes, and it is soft e Mineral species	NaCl	2–2.5

How to use the index

The index is a log table, not a catalogue of names. Read down the hardness column first: if your specimen is scratched by a knife, you are looking in the upper part of the list; if it scratches glass, you are in the lower part. Two or three sheets will then cover the whole plausible range, and the field tests at the top of each sheet will separate them.

Start with the group your specimen most resembles, not with the name you hope it is.
Run the tests in the order given on the sheet. They are ordered so that the cheapest and most decisive test comes first.
Record the number, not the adjective. Write 6, not hard. Write greenish-black, not dark.
If two sheets both seem to fit, go to the comparison sheet where one exists — the four comparison sheets in this collection cover the pairs that are most often confused.

What each sheet contains

A specimen plate, a properties table, an ordered list of field tests with the result each should give, the narrative sections, representative localities with coordinates, the minerals or rocks most often confused with it and how to separate them, storage and handling notes, and the key points in five lines. Sheets are published on a schedule; anything not yet live is absent from the index, the search box and the site map.

Properties: hardness on Mohs' scale, streak, lustre, cleavage, fracture, colour, crystal system, habit and grain index.
Field tests: four tests per sheet, each with the exact expected result, not a range.
Locality: three representative places with coordinates and a note on what occurs there.
Handling: the hazards that actually matter — lead, sulfide dust, acid, deliquescence, cave protection.

A word on the plates

Each sheet is illustrated with a generated wireframe rather than a photograph, because a schematic can carry the diagnostic information and a photograph cannot. Crystal forms are projected polyhedra; line weight is scaled to the mineral's hardness, dashed traces mark cleavage directions, and a seam marks characteristic twinning. Rocks, which have no crystal form, are drawn as fabric plates showing the texture that identifies them: grain mosaic, bedding laminae, vesicles, or conchoidal fracture.

Publication schedule

19 sheets are live. A further 11 are written and scheduled, and go live on their dates.
Unpublished sheets are absent from the index, the search box, the category pages and the sitemap, and their URLs return 404 until they go live.
The index tables and category counts always equal what is actually live; nothing is listed that cannot be opened.

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