Indholdsfortegnelse for August 2025 i Rock and Gem

When a magnitude 7.7 earthquake ripped across Myanmar last March, 3,000 people were killed instantly and damage rippled into Thailand, where a high-rise building under construction collapsed. The epicenter was located on the Sagaing fault, which runs 870 miles straight down the center of Myanmar. A so-called right-lateral strike-slip fault, the Sagaing marks the margin where two big tectonic plates—the Indian and the Sunda plates—collide and slide past one another, much as the North American and Pacific plates slide past one another along the San Andreas Fault in California. Like San Andreas, Sagaing is highly active and has unleashed major quakes for centuries, but why was this time so deadly? Per an article by journalist Alexandra Witze in the journal Nature, the quake of March 28 didn’t simply involve typical…

In articles, blogs and online posts, they’ve been saying it for months: the Axial Seamount is about to erupt! Perhaps by the time this article hits the press, it will have come true. But as I write, it remains wait-and-see, as if the volcano is teasing. Axial Seamount is an underwater volcano 300 miles off the Oregon coast. It’s fed by the Cobb-Eikelberg hotspot along the Juan de Fuca Ridge west of the Cascadia Subduction Zone. When a hotspot intersects a spreading mid-ocean ridge not far from a major subduction zone, one should expect a lot of action. And action there has been. The Axial Seamount has erupted several times in recent years. Sensors have been dropped on its flanks going back to 1992, and they helped detect a submarine…

Over a year ago, I described research by Lei Ye and Huishen Peng (Fudan University, China) on efforts to develop a sodium battery that might give lithium batteries a run for the money if only their lab experiments could be scaled up to industrial levels. Lithium—the current darling of a green-energy future—is somewhat scarce and costly to mine in an environmentally friendly way, but sodium is all around us, from salt mines to oceans covering 71 percent of the Earth’s surface. Accessing it easily and cheaply is no problem at all. Now, in the journal Science, journalist Robert F. Service reports on amazing progress within the past year with sodium-ion batteries matching low-end lithium batteries. Indeed, Service notes they are already powering scooters and electric vehicles. Most experts caution that…

Most helium floating around Earth’s atmosphere today sports two neutrons and is believed to be released as a by-product as other elements, like uranium, decay. But scientists say that when the Big Bang kick-started our universe, there was a primordial helium, one with a just single neutron. A similar sort of helium has been found in the gases released by some volcanic eruptions. Now, one team of scientists thinks they know why. As they outline in the journal Physical Review Letters, Haruki Takezawa (The University of Tokyo) and colleagues believe that helium from the days of the Big Bang may be packed into the Earth’s solid iron core. To test their theory, they squeezed iron and helium under intense pressures and heat to simulate conditions at the center of the…

Fluorite Ridge, approximately ten miles north of Deming, New Mexico, has several accessible former fluorite mines and prospects. Most of the area is administered by the U.S. Bureau of Land Management, and any unclaimed lands are generally open to collecting. The mines in the lower elevations are reached by an unpaved road that is well maintained and accessible by a two-wheel drive vehicle, while the mines in the higher elevations are accessible by a four-wheel drive vehicle or hiking. Most of the fluorites at the mines and prospects are white to light green and occur as fissure veins in granitic and volcanic host rocks. FLUORITE & INDUSTRY Fluorite (CaF2) is calcium fluoride. While this is a simple chemical formula, fluorite occurs in a wide range of colors. It is often…

Peridot is the bright green gem-quality variety of the mineral forsterite, a magnesium silicate. Both are commonly referred to as “olivine,” which is intended to refer to samples with a composition between forsterite and fayalite (an iron silicate). While many gemstones can be found in multiple colors, peridot occurs in shades that range from yellow-green to olive or brownish-green. The gem’s green color is because of its iron content, with higher concentrations producing deeper hues. How It Forms Peridot forms deep within the Earth’s mantle, between 20 and 55 miles below the surface. Volcanic activity, particularly basaltic lava flows, brings peridot to the surface. It grows under high temperatures and pressures and is associated with mafic and ultramafic igneous rocks. Rarely, but famously, peridot is also found in pallasite (stony-iron)…

You love your jewelry. Maybe you’ve worn a piece every day for years only to notice one day that the stones appear cloudy, the metal looks dull, and the whole piece has lost its original sparkle. You want to restore its beauty—but where do you begin? Caring for jewelry is a lot like maintaining a car: it requires regular attention, a bit of knowledge, and, at times, professional help. While some upkeep can be done safely at home, other tasks should be left to skilled jewelers to avoid costly mistakes. As a professional jeweler, I’ve seen my fair share of horror stories. Just yesterday, another store owner stopped by to pick up her estate restorations from our trade shop, Bench No. 5. She asked about a customer’s ring that had…

The truism that we know more about the surface of the Moon and Mars than Earth’s seafloor turns out to be true. Sure, we’ve mapped large portions using technologies like sonar and satellite altimetry. But how much of the deep sea floor has been seen by direct visual observation, either by human eyes or cameras in research submersibles? Less than 0.001percent! Writing in the journal Science Advances, a team led by Katherine Bell (Ocean Discovery League) says that’s “approximately a tenth the size of Belgium.” And Belgium is one small country. To arrive at this finding, they studied 43,681 records of all known direct observations. Sound like a lot? Well, the vast majority took place in just a few spots, for instance, off the coasts of the U.S., Japan and…

Metals like arsenic, cadmium, cobalt, chromium, copper, nickel and lead have long been mined for their valuable industrial applications. Such applications remain significant and necessary. But in addition to their value, these metals can also be downright toxic, and in mining and smelting them, we humans have spread them far and wide. But just how far and wide? An international team led by Deyi Hou (Tsinghua University, China) undertook to find out. In the journal Science, they describe taking 1,493 regional studies encompassing 796,084 sampling points to map spots where levels of such toxic metals contained within soil samples exceed safety standards for agricultural and human health thresholds. Their map reveals as much as 17% of cropland around the globe exceeds established safety levels for one or more toxic metals.…

Was Spinosaurus the first and only dinosaur known to be fully aquatic? That’s the question explored by science reporter Carolyn Gramling in a cover story of Science News. The question remains at the fore due to the scant fossil record of this enigmatic creature. Indeed, no complete skeleton has ever been uncovered, leaving a jigsaw puzzle with many missing pieces. To help find the pieces, Nizar Ibrahim (University of Portsmouth, UK) has been digging ever deeper in the Kem Kem beds of Morocco where, with every trip, he brings back ever more pieces. They convince him Spinoaurus gave up life as a landlubber and nimbly swam rivers and lakes in search of fishy meals. He points to dense bones, short and muscular hind limbs, the position of nostrils, and a…

One of the most common myths about gemstones is that some of them cannot break. The hardness of diamond, for example, leads some to believe that the gemstone can be worn on any occasion without worrying that it can be damaged, or that the high polish and sharp facets of gem-quality sapphire cannot be marred by continuous and, perhaps, careless wear. The truth is that, although some gemstones are more durable than others, none are unbreakable. Depending on the gem and the circumstance, anything from a slight vibration to a hard fall (or a day spent gardening in the backyard) can cause damage. Even diamond, a 10 on the Mohs scale of hardness, can easily “cleave,” or break and chip if struck in a certain direction or knocked against another…

In a classic example of understatement, most Australians simply call it “The Rock.” Rising 1,142 feet in awesome and solitary grandeur above the surrounding flat desert, it is one of the world’s best-known natural features. It’s also a sacred site representing 30,000 years of human habitation and an iconic image of Australia and that nation’s vast Outback. Previously called Ayers Rock, “The Rock” is today known as Uluru (ool-a-roo), a name of great antiquity that even predates the Ice Ages. TECTONIC ORIGIN Geologically speaking, Uluru is an inselberg (“island mountain” in German), a small, isolated mountain that rises abruptly from a level plain. Inselbergs consist of hard, resistant rocks that erode much more slowly than the surrounding rocks. Uluru’s geological story began 550 million years ago with a major, tectonically…

Signs of an iron deposit of immense proportions have surfaced in Australia. Dubbed the Hamersley deposit, it may clock in at 55 billion metric tons and could be worth trillions of dollars. Writing in Proceedings of the National Academy of Sciences, a team led by Liam Courtney-Davies (Curtin University, Australia) looks beyond the economic value. The scientific value to geologists? Priceless! Per conventional wisdom, the Earth’s biggest iron ore deposits formed 2.2 to 2.0 billion years ago during an oxidation event that left banded iron formations (BIFs) at spots around the Earth. BIFs formed when oxygen levels in our ancient atmosphere reached a tipping point and reacted with iron dissolved in seawater to leave behind the huge deposits of iron oxides that we mine today. But Courtney-Davies’ team has dated…

It’s being described as “an irreversible decline in soil moisture.” Earth’s hydrological cycle, it seems, has entered a new phase, and it is global in scale. As outlined in the pages of the journal Science, Ki-Weon Seo (Seoul National University, South Korea) and an international team of colleagues integrated many widely respected geophysical datasets to track how Earth’s water storage seems to have changed over four decades. Their compilation shows a notable and persistent decline in terrestrial water storage, as prominently displayed by prolonged drought conditions in places like the American Southwest. The authors cite both climate change and “the Chandler wobble,” or the periodic oscillation of the Earth’s rotational axis, which can be affected by shifts in mass on the surface of the planet. Changes caused by shifting terrestrial…

Everyone loves genealogy. The further back you trace, the better. Grandma’s aunt even traced us to a fancy French count—no matter that he died a confirmed bachelor. News of more distant ancestors has been making a splash of late. During the Pleistocene, three sorts of humans hunted mammoths: Homo sapiens, Neanderthals, and the lesser-known Denisovans. Those lesser-knowns are now a bit better-known thanks to a recently identified jaw from Taiwan, which single-handedly extends the Denisovan range from the cold of Siberia and Tibet to warmer subtropical climes. The announcement was made in the journal Science by Takumi Tsutaya (University of Copenhagen, Denmark & SOKENDAI, Japan) and colleagues. In the journal Nature, a team led by Rosa Huget (Spanish National Research Council) reports discovering the oldest known Western European in the…

With Mars exploration, it’s two steps forward, one step back. Looking forward, as reported in the journal Science, a team led by Benjamin Tutolo (University of Calgary, Canada) reports the Curiosity Rover (wandering Mars since 2012) has identified iron carbonates in the form of siderite on the Red Planet’s surface inside Gale crater in drill samples pulled from a sulfate-rich layer. This indicates long ago a carbon cycle operated on Mars as it operates on Earth today. Apparently, an atmosphere dense in carbon dioxide interacted with surface liquid water and crustal rocks. Earlier, another step forward was reported in the journal Nature. The Perseverance rover, which landed in 2021, spotted a rock formation resembling leopard spots. Scientists called these “an intriguing signal” of ancient microbial life, although they gave such…

In the collection of Middle Eastern folktales One Thousand and One Nights (Arabian Nights in English) Sinbad the Sailor recounts, “As I walked through this valley, I perceived it was strewn with diamonds, some of which were of surprising bigness.” While Sinbad and his adventures are fictional, scholars believe that his “valley of diamonds” refers to Golconda, India. As the world’s first source of diamonds, Golconda has yielded some 10 million carats, including many legendary stones of exceptional quality that were coveted by sultans, sheiks, shahs and kings. Although Golconda ceased production 200 years ago, its diamonds remain part of the cultural fabric of India, the Middle East, Europe and the United States. Even the word “Golconda” has endured as a metaphor for a place of great wealth. THE FIRST…

Maw Sit Sit is a rare, electrifying green stone only found in the surrounding region of the village of Tawmaw, north of Myanmar. Sometimes called “Chrome Jade,” many believe this stone to be a type of jade or jadeite. Instead, it’s a metamorphic stone comprised of kosmochlor, clinochlore, albite and many other minerals. Kosmochlor, a sodium chromium pyroxene mineral, is what makes up the vibrant green coloring. Interspersed are different shades of green, swirls and dots of black and sometimes white striations. This stone is often used in jewelry and even carved pieces because of its eye-catching appearance. HISTORY BEHIND MAW SIT SIT Swiss gemologist Edward J. Gubelin found this material in the early 1960s after an invitation brought him to the Upper Burma area to take an excursion to…

This question occurs again and again, whether you pick up a pebble while walking, find a crystal in the mountains, find gold or silver shiny chunks in a spoil heap at an ore mine, trip over the curb or look at a beautiful piece of jewelry. Time and again, you want to know what that mineral is, what kind of rock lies before you, what type of gemstone glitters with such beautiful colors. The purpose of this book is to answer such questions — as a constant companion when hiking, travelling, mountaineering, collecting minerals or when searching quarries and spoil heaps, at mineral fairs and even at the jeweler’s. There are a few basic points to keep in mind: With the exception of mercury, minerals are always solids. No matter…