I can still remember the first time I saw the Tonglushan Chalcopyrite Spheres. It wasn’t in 2019 when the material first debuted on the market, but in early 2025 on Instagram, when I saw a parcel offered by a Chinese wholesaler. I was immediately mesmerised by the aesthetics and strong geometric character of the specimens, but I was also afraid they were too good to be true. They were surreal, beautiful, and unlike anything else I had seen in the mineral world before. Even though they were intriguing, I didn’t know how to feel about them.

My first instinct was to send them to Luke Timberlake from The Salt Shack for a second opinion. He’d developed a reputation for being an excellent mineral sleuth, and was well known on social media at the time for myth busting ‘fake’ material. If anyone was going to know the truth, or know the best way to find out, surely it was going to be him. Unfortunately though, I ended up sending him a disappearing story, and by the time he had seen my message the original content had all but vanished. I never ended up getting his thoughts on those pieces. What happened instead, was a journey down a rabbit hole I could never have imagined.

The material first rose to prominence when specimens were brought to market by The Arkenstone in 2019, one of the industry’s most trusted and well known fine mineral dealerships. They were also initially skeptical, but their mining source had spent over a decade establishing trust, and so instead of dismissing the pieces they began to investigate further.

One of the larger spheres was cut open and analysed at the University of Arizona. They used energy-dispersive x-ray spectroscopy (EDS) to confirm that the material was authentic copper iron sulfide (chalcopyrite) purely throughout – both internally, and externally. Not only that, but the internal structure demonstrated organised and radial growth, ruling out carved, assembled or manufactured forms. In addition to this, Stuart Mills at Museum Victoria also identified chalopyrite and pyrrhotite by X-ray diffraction.

The turning point came when matrix specimens began appearing. Until then, most examples had been recovered as loose floaters from the bottoms of open cavities. Eventually, specimens still attached to the surrounding mudstone were collected from the roof of the pocket itself on request of The Arkenstone. These showed distinct reaction zones between the spheres and the host rock, suggesting the chalcopyrite had formed within the matrix before later being liberated into the cavity.

The material appeared to be an unusual variation of a process that was already known, and The Arkenstone compared the spheres to classic blister copper specimens from Cornwall and Connecticut, where metallic masses form rounded shapes within the surrounding rock before later exposure reveals them. The broader idea was not entirely without precedent.

Initially, the results appeared to support the earlier work. The material once again tested as chalcopyrite using EDS, which seemed to reinforce the conclusions already reached by The Arkenstone and other researchers. Then the pandemic arrived, halting further study for many months.

During that time, something odd happened. The polished surface of the sample sphere had been left exposed to the air inside the museum, and when staff eventually returned, they discovered that crystals of calcium sulfate had actually grown across the surface.The Smithsonian then began a much more detailed investigation of the specimen, being curious about how and why this had occurred. What they found completely changed the trajectory of the conversation.

Inside the spheres were porous regions containing smaller chalcopyrite spherules surrounded by other mineral phases. Alongside quartz, muscovite and feldspar, researchers identified both calcium sulfate and calcium sulfide.

The presence of calcium sulfide was an absolute bombshell. It’s an uncommon and unstable compound that’s more often associated with meteorites than terrestrial environments. Most mineralogists will go their entire careers without encountering it, and there are only a handful of natural occurrences known worldwide. Usually, it’s found in environments that require oddly specific and highly unusual conditions.

One of the best known examples comes from burned coal seams near the Dead Sea, where a very unusual chemical environment produced minerals that simply wouldn’t have formed under ordinary circumstances. In this case, gypsum, hydrocarbons and sulfur were all present, temperatures became very high, and oxygen was restricted (what we call a reducing environment).

The presence of calcium sulfide can be considered an anomaly so bizzare, that Mindat founder Jolyon Ralph has attached a disclaimer to the Tonglushan locality page acknowledging the ongoing contradictions that have brought their authenticity into question:

The disclaimer had originaly stated that the specimens appeared to be sintered and manufactured by Chinese wholesalers, but this wording has since been edited back. To many collectors, his original disclaimer effectively settles the debate, and I’ve seen the statement quoted countless times online as though it were a final conclusion. As things stand today, the wording itself stops well short of declaring the specimens fake. To some, “made up of chalcopyrite spherules bonded together” immediately suggests assembly or manufacture, but the observation itself doesn’t explain how those spherules became bonded together, nor does it identify the mechanism responsible for creating them such as glue, resin or any other binding agent, which have never been identified in this material. Observation and explanation are not the same thing.

The presence of calcium sulfide inside of the Tonglushan spheres is highly problematic in any scenario. If the spheres formed naturally, then what kind of environment could have produced them? If the spheres were manufactured, how did it get there?

At this point, we have to look more closely at the Tonglushan Mine itself. This Copper Mine near Daye in Hubei Province is not just any other mine, but is the world’s oldest continuously worked copper mining district on Earth, with a history stretching back over 3,500 years all the way into the Chinese Bronze Age.

Ancient smelting ruins still exist at the site today, remnants of the immense copper production that helped supply the bronze industries of early China during the Western Zhou Dynasty. Archaeological estimates based on surviving slag suggest that between 80,000 and 100,000 tons of copper may have been extracted here over centuries of activity. If there is a locality on Earth capable of producing chemistry that doesn’t fit neatly into our existing categories, Tonglushan seems like a reasonable candidate.

Just like the Dead Sea locale, Tonglushan also has abundant sulfur bearing copper ores, documented gypsum occurances, evidence of ancient smelting and large scale combustion, and thousands of years of metallurgical activity. Whether these ingredients were in the same place at the same time, in such a way as to create calcium sulfide, is a question we have yet to answer.

One of the most common arguments put forward by skeptics of the material is that the calcium sulfide points towards some kind of industrial or anthropogenic origin. Theories range from modern workshop fabrication including glue and coatings, all the way to them being a byproduct of historical mining or metallurgical processes associated with the locality itself. We must remember that unlike an ordinary mineral deposit, Tonglushan has experienced countless generations of human activity.

One possibility is that it represents an unusual geological process, while another is that it reflects an industrial or metallurgical process that has not yet been fully understood. The presence of both calcium sulfate and calcium sulfide suggests a complex chemical history involving multiple stages, but at present neither a natural nor artificial model fully explains all of the observations.

Perhaps the biggest assumption in this entire debate is that the answer must be either natural or artificial, but perhaps there are other options we haven’t considered yet.

While it’s true that producing calcium sulfide artificially is theoretically possible under the right conditions, Tonglushan isn’t an untouched alpine fissure or a remote pegmatite hidden deep in the wilderness. The landscape has been worked and altered by humans, on an enormous scale, continuously, for thousands of years. Mining, smelting, sulfur rich combustion, groundwater movement and mineralisation have all been interacting within the same environment for longer than most civilizations have even existed. There’s every chance there could be an unusual interaction between the two worlds occurring, the extent of which we have no idea about yet.

When we describe something as “natural” or “artificial”, we’re usually talking about processes that are easy to separate. Tonglushan may not be one of those places.

If the spheres are modern industrial byproducts, then how did they acquire the organised internal textures observed when they were cut open? How did they become incorporated into matrix specimens displaying reaction zones between the spheres and surrounding mudstone? Why do they appear distributed throughout natural cavities underground? And perhaps most importantly, if the calcium sulfide originated through some industrial process, then how did this occur?

To simply state that the spheres are sintered, lab grown or artificially manufactured a conclusion, not an explanation.How could such a process account for the internal textures, matrix relationships, chemistry and morphology observed in the material. Any artificial model must explain all of these observations, not just the ones that support it.

We must remember that calcium sulfide and calcium sulfate appeared together within a single specimen. One of them formed under conditions where oxygen was largely absent, while the other represents sulfur interacting with oxygen and water – complete opposite ends of the sulfur cycle. It’s a remarkable combination, and yet somehow both phases are evident within the same piece. If the identification is correct, the specimens may be preserving evidence of multiple chemical environments and multiple stages of alteration within a single object.

The Smithsonian specimen didn’t merely contain calcium sulfate internally, but actively grew new calcium sulfate crystals on its polished surface while sitting exposed to air. The specimen appears to carry within it evidence of multiple chemical environments layered on top of one another. Are we perhaps looking at different chapters of the same story, preserved within the specimen?

Maybe there is a straightforward explanation that has yet to be discovered.

The spheres still test as genuine chalcopyrite years after their original discovery. No glue or adhesive has ever been reported. The internal textures remain difficult to dismiss, there are matrix specimens to consider, and trying to explain the calcium sulfide leaves us with more questions than answers.

The deeper researchers dove into this investigation, the less straightforward it became. In most authenticity controversies the evidence gradually converges towards an answer but here, the opposite has happened.

If these were simple workshop fakes, the conversation would have ended years ago. Instead, the specimens continue to circulate through some of the most respected corners of the mineral world. In June 2024 the Mineralogical Record reported on a rare appearance:

After first seeing them on Instagram I immediately began researching and soon after, I was hunting down a specimen for my own personal collection – a process that has taken just shy of 18 months. Aside from the phenomenal aesthetics, the lack of resolution and ongoing interest from the fine mineral world is precisely what makes these specimens compelling. Every answer seems to create another question. Whether future work eventually demonstrates an entirely natural origin, a partially anthropogenic process, or something occupying a space between the two that we don’t yet fully understand, these specimens remain one of the most thought provoking modern mineral finds to emerge from China in recent years.

References

The Arkenstone 1

The Arkentstone 2

University of Arizona

Stuart Mills at Museum Victoria

The Smithsonian Testing

The Mineralogical Record

Weinreich Minerals

Mindat – Tonglushan Page

Mindat – Forum Discussion