Reading
Articles
Articles are presentation, not canon: they are written on top of the structured claim registry, and every checkable statement cites the claims — and therefore the sources — it rests on.
earth materials
Atoms, elements and isotopes
Three numbers describe an atom, and geologists use all three for different purposes. Confusing them is the commonest error in writing about geochemistry — and one of them is not a single number at all.
tectonic context
Cratons, shields and platforms
A craton is stable continental lithosphere. A shield is the part of one you can see. They are not two things, and the difference matters more than the words suggest.
minerals
Crystal structure and substitution
A crystal is a set of sites of particular sizes and charges. Which ions can occupy them decides what the mineral is, how its composition varies, and — as it turns out — where elements go in the Earth.
how we know
Dating the Earth
Radiometric dating is precise, well understood, and does not measure what people usually think it measures. Understanding what it actually records explains why the age of the Earth had to come from meteorites.
inside earth
Earth’s internal heat
The engine that moves plates, builds mountains and melts rock runs on two fuels, not one: heat inherited from the planet’s formation, and heat still being made by radioactive decay. Separating the two took a particle detector.
geochemistry
Element partitioning
The reason the Earth is not chemically uniform is a matter of fit: whether a particular ion suits a particular site in a particular crystal, under particular conditions. Everything else follows from that.
mineral systems
Formation is not preservation
A mineral system can run to completion and leave nothing behind. What survives to be found is decided long after the metal stopped moving, by oxidation, uplift, erosion, metamorphism and burial — and what is found today is never quite what formed.
rifts
How continents rift
Breaking a continent is a sequence, not an event — and it does not always finish. East Africa and the Red Sea are the same process caught at two different stages.
earth
How Earth formed
Earth has no birth certificate. Its own oldest rocks were destroyed by the planet it belongs to, so the age of the Earth had to be read from objects that never changed — and that indirection is the first thing worth understanding about deep time.
volcanoes
How magma forms and why volcanoes erupt
Magma and lava are the same material in different places. Whether an eruption pours or explodes is decided long before the surface, by what the magma is made of — and volcanoes do not all form the same way.
mountain ranges
How mountains form
Two plates collide and mountains rise is a description of one mechanism, not of mountain building. Ranges are raised in several different ways, and the Andes and the Himalaya are not the same story.
oceans
How ocean basins form
The largest mountain range on Earth is underwater, and it is a factory. Everything about the ocean floor — its age, its magnetism, its eventual disappearance — follows from what happens along that ridge.
rocks
How rocks form
Three classes, three routes — and each rock carries a legible record of the conditions that made it. Grain size is a clock; foliation is a compass.
plate tectonics
How subduction works
Subduction is where the ocean floor ends. It carves the deepest features on the planet, builds volcanic chains, generates the largest earthquakes — and its central mechanism, how the magma is made, is still argued over.
plate tectonics
How tectonic plates move
Plates diverge, converge and slide past one another along narrow boundary zones. Each style of boundary leaves a distinctive signature: new ocean floor, deep trenches and volcanic arcs, or long transform faults like the San Andreas.
how we know
How we know what is inside Earth
No one has seen the mantle, and no one ever will. Everything below the shallowest crust is reconstructed from waves recorded at the surface — which is why the interior chapters of Earth science are written in the language of inference, not observation.
deposits
Known deposits are not a map of what exists
A catalogue of found things is a record of finding. Where the dots cluster, people looked. Reading that as a map of endowment reverses the causation, and it is the single most tempting thing to do with this corpus.
tectonic context
Large igneous provinces: observed, and not explained
A definition made entirely of size, rate and position — and deliberately silent about cause. Lithoen records the provinces and does not attribute them.
inside earth
Lithosphere and asthenosphere
There are two ways to slice the Earth’s interior, and they do not line up. One divides by what the layers are made of; the other by how they behave. Plate tectonics happens on the second division.
mineral systems
Magmatic nickel-copper systems
Metal that never touches water. A mantle-derived magma swallows enough crustal sulfur to become sulfide-saturated, an immiscible liquid separates, and it collects wherever the flow slows. Occurrences are on most continents; deposits worth the name are in five countries.
mineral systems
Mississippi Valley-type systems
No magma, no heat source, no volcano. Warm salty water moving through limestone deposits lead and zinc at temperatures a domestic oven would exceed — and this system supplies the clearest evidence in the corpus that a geological control is not a geological prediction.
mineral systems
Nickel-cobalt laterites
The only system here whose engine is the weather. Rainwater removes magnesium and silicon from ultramafic rock over millions of years and leaves nickel behind — and the same uplift that exposes the rock destroys the profile that concentrates it.
deposits
Occurrence, deposit, resource, reserve
Five words that are used interchangeably and mean five different things. Only the first two are geological, and the definition of the second contains the word "might".
mineral systems
Ore is not a geological word
Mineralisation, deposit, resource, reserve and ore are five different things, and only the first two are geological. Lithoen can describe rock; it cannot say what is worth mining, and this article explains why the distinction is enforced by machine rather than left to good intentions.
tectonic context
Plates, models, and what a boundary line is
Every plate boundary you have ever seen drawn belongs to a model. Model PB2002 divides Earth into fifty-two plates and marks thirteen more regions where it says a rigid plate does not describe the motion at all.
mineral systems
Porphyry copper systems
The archetype: a shallow granitoid porphyry, an exsolving magmatic fluid, kilometres of altered rock, and copper spread thinly through an enormous volume. It supplies most of the world’s copper and the model that describes it says many of its controls are still poorly understood.
geologic time
Reading deep time
The geological time scale has two parallel vocabularies, and confusing them is the commonest error in writing about Earth history. One names bodies of rock; the other names lengths of time.
mineral systems
Stratiform chromite systems
Layers of chromite metres thick and tens of kilometres long, holding most of the world’s chromium. How they form is not settled — the deposit model says so in its own words, and this article keeps that sentence in view.
geochemistry
The geochemical reservoirs of Earth
A number for “the Earth” is not a number at all until it says which Earth. Bulk Earth, bulk silicate Earth, the crust and the upper continental crust are four different volumes with four different compositions.
inside earth
The layers of the Earth
Beneath its thin, brittle shell, the Earth is organised into layers — by what they are made of, and by how they behave. The distinction between the two ways of slicing the planet is where plate tectonics begins.
inside earth
The mantle
The mantle is the largest part of the Earth, and almost everything commonly said about it is wrong in the same way: it is not molten. It is solid rock that flows.
geochemistry
The rare-earth elements
They are not rare. Cerium is more common in the crust than copper or lead, and every one of them except promethium is more abundant than gold. What is rare is the geology that concentrates them.
rocks
The rock cycle
The rock cycle is usually drawn as a circle. It is better understood as a network: many possible pathways between materials, and no requirement that any particular rock travel the whole loop.
mineral systems
Volcanogenic massive sulfide systems
Seawater sinks into hot ocean crust, comes back up at 400 degrees, and drops its metal when it hits cold water. It is the one ore-forming system whose engine can be watched running today — which is exactly why its ancient products are so hard to read.
surface processes
Weathering geochemistry
Chemical weathering is a sorting machine. It dissolves some elements, oxidises others, and leaves behind whatever the water could not carry — concentrating elements without any melt or ore fluid being involved.
surface processes
Weathering, erosion and sedimentation
Weathering and erosion are routinely used as synonyms. They are not: one breaks rock down where it lies, the other moves the pieces. The distinction is the whole reason sediment ends up sorted.
deposits
What a deposit coordinate means
A point on a deposit map is not the deposit. It is a position somebody placed, at a precision they wrote down, inside a zone that may be kilometres across — and the file it arrives in will happily give you thirteen decimal places.
tectonic context
What a geological province is
A named, map-scale region distinguished by its geology and its history. Its identity is the name and the rocks; its outline is a separate thing entirely, and there may be several of those.
commodities
What a mineral commodity is
A commodity is not an element, not a mineral and not a deposit. It is the thing that is sought — and the clearest proof is that one of the most-traded mineral commodities is not a chemical element at all.
mineral systems
What a mineral system is
A mineral system is the whole machinery that concentrates a metal: where the components came from, what moved them, what focused the flow, what made them stop, and what happened to the result afterwards. A deposit is a small part of it, and most of a system is not a deposit.
mineral systems
What an indicator can and cannot tell you
Alteration, structure, a favourable host, the right tectonic setting: each of these is commonly found around mineralisation, and each is also found, far more often, around nothing at all. This is why Lithoen records associations and refuses to score them.
minerals
What is a mineral, really?
Olivine is not a mineral. Neither is feldspar, mica, amphibole or biotite. All five are names in constant scientific use, and none of them names an accepted species — a distinction that matters as soon as anything is written down.
minerals
What is a mineral?
The definition is short and it does real work: it is what separates a mineral from a rock, and it is why a rock’s identity depends on how its minerals are arranged, not only on which ones are present.
deposits
What one row of a deposit database means
Before a dataset can be used it has to be read — not its data, its documentation. Four datasets were read for this phase. Two were accepted, and the two most interesting findings came from sentences nobody would query.
geologic time
Where the Holocene begins
The epoch we live in has a formally defined base — and the way that boundary is defined says a great deal about how geological time is standardised.
earthquakes
Why earthquakes happen
Nothing collides at the moment of an earthquake. A locked surface slips, and elastic energy stored over years is released in seconds.
tectonic context
Why geological boundaries are not exact
A coordinate can be precise to sixty metres and still be in the wrong place. The author of the plate model Lithoen uses says so himself, and everything in the spatial architecture follows from taking him seriously.
tectonic context
Why tectonic context does not prove a deposit
Every mineral system in this corpus is documented in a tectonic setting. Every one of those settings is vastly larger than the systems found in it, and one system barely depends on tectonics at all.
plate tectonics
Why tectonic plates move
The honest answer is that several forces contribute and their balance has been argued over for decades. What changed in the 1990s was not the discovery of the cause but a shift in which cause was thought to matter most.