We Should Get You A Better One
My rhodonite won’t win any beauty contests. The element inside it painted the first human art, armed the Spartans, built the Industrial Revolution, and may power the energy transition.
ACT 1: THE CONTAINER
The collector said it casually, already moving on to the next shelf.
We should get you a better one.
He wasn’t wrong. Our rhodonite from the Morro da Mina mine in Minas Gerais, Brazil — deep crimson bladed crystals set against a matrix of glassy brown cummingtonite — is a perfectly respectable specimen. But he’d scanned the Container the way experienced collectors do, eyes moving fast and efficiently, cataloguing decades of accumulated taste in seconds. The rhodonite didn’t make the cut. He said so kindly, the way someone who genuinely loves minerals tells a small truth, and then he kept moving.
I kept thinking about it.
Not because he was wrong — he wasn’t. A collector’s eye is trained on real things: crystal habit, color saturation, locality, the invisible calculus of what makes one specimen exceptional and another merely present. That’s a legitimate way to look at minerals. It’s probably the right way, if what you’re doing is building a collection worth looking at.
But I’m a curator. And curators, at least this one, have a bad habit of looking through the specimen rather than at it. The rhodonite on that shelf isn’t exceptional. What’s inside it is.
The element is manganese. And the offhand comment about finding us a better specimen sent me somewhere I didn’t expect to go.
But first — the Container.
The vault door is heavy enough that you feel it in your shoulders when you pull it open. It doesn’t swing — it concedes, slowly, like something that has decided to let you in. On the other side is a room about the size of a generous home office, maybe twelve by eighteen feet, and everything in it is grey. The walls are grey. The floor is grey. The safes and locked metal cabinets lining every surface are grey, unlabeled, giving nothing away. The lights run cool and bright — 4000 Kelvin, the color of overcast daylight — and the room echoes when you move. There is no softness in here to absorb sound.
This was intentional. When we designed the Container, we made a deliberate choice to drain it of competition. The room would not have a personality. It would not have warmth or atmosphere or visual interest of its own. It would simply hold things and get out of the way. Because what it holds doesn’t need any help.
Well, most of what it holds does not need any help.
ACT 2: THE PINK STONE AND THE BLACK VEINS
Rhodonite is a manganese inosilicate, (Mn,Ca)SiO₃, crystallizing in the triclinic system with a characteristic rose-red to pink color caused by Mn²⁺ within the structure. It’s genuinely beautiful when it’s beautiful — gem-quality crystals from the Ural Mountains or Broken Hill, Australia can rival any pink gemstone in intensity. The Morro da Mina material has its own character: those deep crimson blades rising out of a glassy brown cummingtonite matrix, the contrast between the two sharp enough to stop you for a moment.
Many rhodonite specimens — particularly those from Franklin, New Jersey — show black veining that cuts through the pink matrix like ink strokes through watercolor. Those veins are not an impurity in the conventional sense. They’re manganese oxide dendrites, formed when the same manganese that gives the pink its color oxidizes at fracture surfaces and grain boundaries, changing oxidation state from Mn²⁺ to Mn⁴⁺ and precipitating as MnO₂.
The mineral is quite literally painting its own portrait in two oxidation states simultaneously.
This is worth pausing on, because oxidation state is the real story of this element across all of human history. The chart below shows the primary manganese minerals and where rhodonite sits in terms of Mn content. Yes, it’s at the low end. No, that’s not the point.
The high-Mn ore minerals — pyrolusite, hausmannite, braunite — are all black. All of them. The mineral only turns pink when it’s sitting quietly in the crystal between two chains of silica, surrounded by enough silicon and oxygen to keep it reduced and beautiful. The moment it oxidizes, it goes dark. That transformation, it turns out, is the engine behind almost everything manganese has ever done for us.
It has been going unrecognized for a long time.
In ancient Magnesia — in what is now Greece or western Turkey — two black minerals were found in the same region and given the same name: magnes, after their place of origin. One attracted iron. The other didn’t, but was used to decolorize glass. To distinguish them, later writers assigned them a sex. The lodestone was the male magnes — active, attracting, doing something visible and dramatic. The pyrolusite was the female magnes — quieter, its action invisible, its chemistry not understood.
From magnesia came manganesum. From manganesum came manganese. And from the same ancient root, by a different path, came magnesium — two different elements sharing an etymology, one of them accidentally linked to magnetism despite being entirely non-magnetic.
Manganese is the least magnetic of the transition metals. The female magnes, it turns out, was named for attraction and has none.
The collector would have felt right at home in ancient Magnesia.
ACT 3: THE FIRST MARK
Before there was writing, before there was agriculture, before there was anything we would recognize as civilization, there was manganese.
Specifically, there was pyrolusite — MnO₂, manganese dioxide — ground to a fine black powder, mixed with animal fat, and pressed by a human hand against a cave wall. The paintings at Lascaux. At Altamira. At Chauvet. The bison and horses and aurochs that have survived thirty thousand years in the dark were put there with manganese (with charcoal and soot) — manganese, chosen specifically because its chemical stability meant the pigment would not fade, would not migrate, would not be undone by time.
We do not know if the people who made those paintings understood why the black held so well. They knew it worked. They came back to it, generation after generation, extracting pyrolusite from the same deposits, carrying it into the deep chambers where the art was made. One of the oldest, if not the oldest, sustained materials science programs in human history, and the active ingredient was the same element sitting in the pink silicate on my shelf.
Pyrolusite — black, heavy, unremarkable to look at — is Mn⁴⁺. Manganese in its highest common oxidation state, fully oxidized, stripped of electrons. It is not pink. It will never be pink. That requires the element to calm down considerably, to sit in a silicate structure as Mn²⁺ with a full complement of electrons, surrounded by oxygen and silicon in a structure that coaxes out the rose color we find beautiful enough to carve into imperial tombs.
The cave painters weren’t thinking about oxidation states. But they were, without knowing it, exploiting the same chemical flexibility that makes this element so remarkable — its ability to exist in multiple oxidation states, each one behaving like an almost entirely different material. Black and permanent for pigment. Pink and beautiful for jewelry. And as we’ll see, other oxidation states entirely for the things that came next.
The darkness of Lascaux and the pink of a Brazilian mine are the same atom, differently charged.
That’s worth sitting with for a moment.
ACT 4: THE GLASSMAKERS’ SOAP
Here is a question worth asking: when did human beings first make something truly transparent?
Not translucent — not the thin-scraped animal hide stretched over a window opening, not the oiled parchment that let in a grey approximation of daylight. Truly transparent. Something you could hold up and see the world through clearly, something that separated you from the weather without separating you from the light.
The answer is glass. And the answer to how they made it clear is manganese.
The problem with early glass is iron. Sand — the raw material of glass — is almost never pure silica. It contains iron impurities, and iron in glass is not neutral. Depending on its oxidation state, ferrous iron (Fe²⁺) tints glass blue-green; ferric iron (Fe³⁺) pulls it toward yellow. The result, without intervention, is glass the color of a shallow harbor — attractive in its way, but not transparent. Not useful for seeing through.
Egyptian glassmakers at Amarna were working with this problem as early as 1500 BCE. Roman glassmakers systematized the solution by around 100 CE, and it spread through the empire from workshops in Alexandria. The secret ingredient was pyrolusite — the same black manganese dioxide the cave painters had been grinding for pigment for twenty-eight thousand years before anyone thought to put it in molten glass.
What pyrolusite does in a glass melt is chemically elegant. Mn⁴⁺ oxidizes the Fe²⁺ to Fe³⁺ — the stronger blue-green absorber becomes the weaker yellow absorber — while the Mn⁴⁺ itself is reduced to Mn²⁺, which in small quantities is nearly colorless. Two problems cancel each other out. The glassmakers called it their soap — sabon de verre in later French usage — because it cleaned the color from glass the way soap cleans dirt from cloth. They didn’t know they were running a redox reaction. They knew it worked.
Medieval Venetian glassmakers inherited this knowledge and refined it. By the 14th century, the workshops of Murano were producing glass of extraordinary clarity using manganese dioxide sourced from deposits across Europe. The transparency of Venetian glass — that quality that made it so coveted, so expensive, so widely imitated — was built on manganese chemistry that traced an unbroken line back to Alexandria, and before that to Egypt, and before that to the same pyrolusite deposits that stocked a cave painter’s kit.
Then something unexpected happened. Centuries later, in the older houses of New England, people began noticing that their clear window panes were turning purple.
Not all of them. Not quickly. But glass that had been installed in the 18th and early 19th centuries — glass made with manganese dioxide as a decolorizer, in the tradition that stretched back to Rome — was slowly, visibly, changing color in the sunlight. Developing a lilac, then an amethyst hue, deepening over decades.
A New England glass manufacturer named Thomas Gaffield investigated in the 1820s and found the culprit: the manganese. The Mn²⁺ that had been doing its quiet decolorizing work was being photo-oxidized by sunlight — the same photochemical process, driven by the same light energy, reverting it back toward its original oxidized state. The glass was, in a sense, remembering what the manganese had been before the iron reduction happened. It was returning, molecule by molecule, to its cave-painting self.
American glass collectors now prize solarized amethyst glass as a mark of authenticity — a signature of age, of a particular era of manufacture. What they’re looking at, held up to the light, is manganese chemistry running slowly in reverse. An unintentional clock. The glass is purple because the manganese is oxidizing, because the sun is doing what sunlight does, because the element that cleaned the glass two hundred years ago is now, patiently, undoing its own work.
There is a word for this in mineralogy. We call it alteration.
ACT 5: THE ELEMENT THAT WON WARS — AND NOBODY KNEW IT
There is a persistent mystery in ancient military history.
The Spartans were not the largest army in the ancient world. They were not always the best supplied, the most numerous, or the most strategically sophisticated. But their steel had a reputation that preceded them — weapons that held an edge longer, armor that absorbed impact differently, metal that behaved under stress in ways that their enemies’ metal did not. Ancient writers noted it. Modern historians have puzzled over it. The explanation, when it finally came, had nothing to do with Spartan smithing technique or secret forging knowledge.
It was the ore.
The iron deposits available to Spartan metalworkers happened to contain manganese — not by design, not by understanding, but by geology. When that ore was smelted, trace amounts of manganese entered the iron, and the resulting metal was measurably harder, tougher, and more resistant to deformation than iron produced from cleaner deposits elsewhere. The Spartans had a materials advantage they could neither explain nor reproduce intentionally. They just knew their metal was better. They were right. The reason was sitting in the ore the whole time, invisible, doing what manganese does.
This would remain unexplained for roughly two thousand years.
The formal understanding of manganese’s role in steel began to emerge only in the early 19th century. In 1816, a German researcher documented that iron alloyed with manganese was harder without becoming more brittle. Patents followed in Britain. Industrial production of ferromanganese began. And then, in 1856, a British steelmaker named Robert Forester Mushet solved a problem that had been threatening to derail the entire Industrial Revolution.
Henry Bessemer had invented his converter — the process that would make mass-produced steel possible, that would build the railroads and the bridges and the structural skeletons of modern cities. But the Bessemer process had a flaw: it left excess oxygen and sulfur in the steel, making it brittle and unpredictable. Unusable at scale. Mushet’s solution was to add spiegeleisen after the blow — a pig iron rich in manganese and carbon. The manganese scavenged the oxygen and sulfur, the carbon restored the carbon content, and the steel that came out the other end was consistent, workable, and strong.
Mushet saved the Bessemer process. The Bessemer process built the modern world. And the active ingredient in Mushet’s fix was manganese.
Then Robert Abbott Hadfield took it further. In Sheffield in 1882, Hadfield produced an austenitic manganese steel containing roughly 12% manganese — and discovered something that seemed almost physically impossible.
The more you hit it, the harder it got.
If that sounds familiar, it should — Marvel’s writers were working from real materials science when they dreamed up vibranium. The Black Panther suit doesn’t just resist impact; it absorbs and stores it. Hadfield got there first, in Sheffield, in 1882.
Impact didn’t damage Hadfield steel. It strengthened it. The technical term is work-hardening: manganese stabilizes the austenite phase of iron so that deformation induces martensitic transformation at the surface while the bulk remains tough and ductile underneath. In practical terms, you could build things that needed to be simultaneously hard on the outside and resilient within — railway track switches that grew stronger under every passing train, rock crushers, and eventually, tank treads and armor plate. The violence, counterintuitively, was doing the maintenance.
During the Second World War, the Ural Mountains — the same geological formation that had been producing rhodonite for imperial Russian lapidary work, the same mountains the Tsarina’s sarcophagus came from — were supplying roughly 70% of the Soviet Union’s manganese. The decorative stone in the Peter and Paul Cathedral and the armor on the T-34 tank share a mineralogical address. The pink and the black. The beautiful and the brutal. Coming out of the same mountains, in the same decade, for completely different purposes.
No one was thinking about oxidation states (I don’t think). No one was thinking about rhodonite. They were thinking about steel.
But the element doesn’t care what you’re thinking. It just performs.
ACT 6: THE PATIENT ELEMENT
In 1866, a French engineer named Georges Leclanché sat down and invented the battery that would eventually power the modern world — not immediately, not dramatically, but with the quiet persistence that seems to characterize everything manganese touches.
The Leclanché cell was simple by the standards of what came before it. A zinc anode. An electrolyte of ammonium chloride solution. And a cathode made of manganese dioxide packed around a carbon rod. Pyrolusite again. The same black mineral that colored cave walls and cleaned glass and silently improved Spartan weapons was now sitting at the heart of an electrochemical cell, doing something entirely new: accepting electrons during discharge, reducing from Mn⁴⁺ toward Mn³⁺, storing and releasing energy.
The cell worked. It was cheap. It didn’t require a liquid electrolyte that would spill — later refinements produced the dry cell, which made portable electrical devices possible for the first time. The flashlight. The portable radio. The transistor radio your grandfather carried. Every alkaline battery you have ever put in a television remote or a child’s toy contains manganese dioxide as the cathode material, running the same basic electrochemical reaction that Leclanché worked out in 1866.
One hundred and sixty years of batteries. The same element. The same oxidation state chemistry.
What makes manganese so useful in batteries is the same thing that made it useful everywhere else: its willingness to change. Mn⁴⁺ accepts electrons readily, becoming Mn³⁺, then Mn²⁺. It does this reversibly, or nearly so, which is the fundamental requirement of a rechargeable system. It is abundant — the 12th most common element in the Earth’s crust, present in accessible deposits on every continent and in extraordinary concentrations on the seafloor in polymetallic nodules that may eventually represent one of the largest untapped mineral resources on the planet. It is relatively non-toxic compared to the cobalt and nickel that dominate current lithium-ion battery chemistry. And it is cheap — orders of magnitude cheaper than the materials it might replace.
Battery engineers have known all of this for decades. The challenge has been getting manganese to behave well enough in rechargeable systems at the voltages and energy densities that modern applications require.
Lithium manganese oxide — LMO, the spinel structure, LiMn₂O₄ — was one of the first serious answers. Insert lithium ions into the manganese oxide framework during charging; extract them during discharge. The manganese cycles between oxidation states to compensate the charge, the spinel structure provides channels for the lithium to move through, and the result is a cathode material that is safer, cheaper, and more thermally stable than lithium cobalt oxide. LMO has been in commercial lithium-ion batteries since the 1990s. It is in your power tools. It is in some electric vehicles. It is, right now, the subject of active research into how to improve its cycle life, reduce its capacity fade, and extend its useful temperature range.
It is also, in a different form, central to my current research.
I work on lithium extraction from brine — the recovery of lithium from the saline waters that saturate the sediments beneath salt flats, the same brines that are now central to the global scramble for battery materials as electric vehicle demand accelerates. The challenge is selectivity: brines contain not just lithium but sodium, potassium, magnesium, calcium, and a periodic table’s worth of other ions, all competing for the same extraction pathways. One of the most promising approaches uses manganese oxide frameworks — synthetic analogs of the natural mineral structure — as ion-selective sieves. The framework’s tunnel geometry and the specific coordination chemistry of the Mn sites preferentially accommodate Li⁺ over larger competing ions.
It is, in its way, the same trick the cave painters were running. Find a manganese oxide mineral that works the way you want it to, and exploit what it naturally does.
The rhodonite on the shelf in the Container started as manganese settling out of a Palaeoproterozoic ocean — somewhere between 2.07 and 1.86 billion years ago, when that ocean was still negotiating its relationship with oxygen. The manganese precipitated as oxide particles in shallow, oxic water, then dissolved and redeposited as it crossed into the euxinic depths below. Eventually it was buried, metamorphosed at temperatures exceeding 600°C, folded, sheared, and exhumed over the better part of two billion years. What came out the other end was queluzite — a manganese silicate-carbonate rock — at the Morro da Mina mine in Minas Gerais, Brazil. The rhodonite is part of that rock, those deep crimson crystals the visible evidence of manganese that survived conditions that would have destroyed almost anything else.
The manganese oxide framework I work with in the lab was synthesized last year in an oven, by my colleague and retired Lawerence Livermore National Laboratory scientist. The geological and the synthetic materials are separated by nearly two billion years but just a few drawers away from each other.
That proximity is not an accident. It’s the reason I’m here. California is rich in minerals and gems, but also rich in amazing scientists to work with.
I came to manganese through the research — through lithium extraction, through brine chemistry, through the problem of getting one specific ion out of water that contains everything else. But I stayed because of what manganese kept turning out to be. Every time I thought I understood it, it opened another door. Cave paintings. Glass. Steel. Batteries. And a lab inside a natural history museum, a synthetic version of its crystal structure being asked to help power the energy transition.
The work is ongoing. The mechanism is not fully understood. My colleagues and I published our most recent findings in 2025 — if you want the crystallography, it’s linked below. But the short version is this: manganese is still surprising us. After thirty thousand years of human use, we are still learning what it does and why.
That is, I think, the most honest thing I can say about why I love this element. Not because we understand it. Because we don’t, quite, yet.
EPILOGUE: BACK TO THE CONTAINER
The collector was generous with his time that day. We talked for a while about rhodonite — the Brazilian deposits, what makes a specimen exceptional, the collector’s market for high-quality material. He knew his stuff. He knows rhodonite the way people who love minerals know things: deeply, specifically, with real feeling for the object.
He was evaluating the specimen. I kept drifting back to the element.
A specimen is a window. What you look through it at depends on what questions you’re carrying when you pick it up. He was carrying aesthetic questions — color saturation, crystal habit, locality, the invisible calculus of what makes one rhodonite better than another. Those are legitimate questions. They are not the only questions.
The collector offered to find us something better. I told him I’d love that. I meant it — a beautiful rhodonite would be a genuine gift, and the right specimen in the right light is its own argument for why these minerals deserve our attention.
But I’ve also become rather fond of the one we have.
It painted the first human mark on a wall. It made Roman windows clear. It gave the Spartans an advantage nobody could explain for two thousand years. It is, right now, on a shelf in a grey container, waiting for the next person who picks it up and asks what it does rather than what it’s worth.
Not much to look at. Performs impressively.
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CURATOR’S NOTES
1. On the durability of manganese pigment in cave environments
The ongoing conservation crisis at Lascaux is frequently misunderstood as a threat to the pigments themselves. It isn’t — not primarily. The danger is to the limestone substrate beneath them. Elevated CO₂ from visitors’ breath dissolves into condensation water on the walls, forming carbonic acid that attacks the calcium carbonate bedrock. When the wall destabilizes, the pigment comes with it. The iron-based ochres — the reds and yellows — are additionally vulnerable to microenvironmental redox changes, and any organic binders used to fix pigments are highly susceptible to biological colonization.
The manganese black, by contrast, is chemically among the most stable pigments in the cave. MnO₂ is already fully oxidized — there is nowhere left for it to go. It doesn’t react meaningfully with carbonic acid under the conditions present. Thirty thousand years of geological time: survived. Forty years of uncontrolled human visitation: the wall begins to fail. Lascaux was closed to the public in 1963 and a replica built nearby. The manganese is still there, in the dark, perfectly intact, waiting. The most durable thing the painters left behind is also the simplest chemically — an element that had already given up everything it had to give.
2. On Hadfield steel and the work-hardening mechanism
The reason Hadfield steel hardens under impact is a function of its unusual phase stability. At roughly 12% manganese, the austenite phase — normally only stable at high temperatures in plain carbon steel — is stabilized at room temperature. When the surface is struck, the mechanical energy induces a localized transformation: austenite converts to martensite at the point of impact, creating an extremely hard surface layer. The bulk of the material remains austenitic and therefore tough and ductile. Repeated impact keeps driving this transformation outward from the surface, so the material literally gets harder the more it is used.
Railway track switches made from Hadfield steel last significantly longer than those made from conventional steel precisely because train wheel impacts are, counterintuitively, maintaining them. The violence is doing the maintenance. This is also why Hadfield steel is nearly impossible to machine — any cutting tool impact hardens the surface faster than it can be cut. It has to be cast to near-net shape or ground, not machined.
3. On the lithium extraction research
The brine extraction work uses a spinel-structured lithium manganese oxide framework as an ion-selective sieve for lithium recovery. The full mechanism — including what we found about how the structure fails under maximum loading conditions, and what that means for practical cycle life — is described in our 2025 paper in the Journal of Raman Spectroscopy. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/jrs.70013
This work was supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, in collaboration with colleagues at Oak Ridge National Laboratory and Mineral Selective Technologies.
Whoops! I made a mistake in the text of the email newsletter. Late night writing and editing... Sorry about the that! The error was in the crystallography, the Mn does not substitute for Si, Mn sits between silica groups in the crystal structure.
And I forgot to add the link to my manganese oxide paper. Good grief! Unfortunately, I only have time to write these posts late at night, so, it's probably going happen again, LOL.
The errors have been corrected in the online version.
Another excellent article! Thanks Aaron.