Indholdsfortegnelse for July 2025 i Rock and Gem

As I was editing this issue, I confess, I really didn’t have a topic for my editor’s letter. I’m not sure why, but my mind was a blank. That is, until I started editing the state rocks and minerals piece by Steve Voynick and the What to Cut column by Ben Kaniuth. It hit me, I’m a native Ohioan and flint is one of my favorites to collect. Ohio’s state gemstone can feel a little ordinary since it’s pretty abundant, but it’s really not. For me, finding flint never gets old. While state designations can seem a little frivolous, I got to thinking about each state and whether these designations matter to the inhabitants. I think they actually do matter. Take Michigan, for instance. Visit there and you’ll find Petoskey…

Pterosaurs were remarkable flying reptiles soaring the skies above dinosaurs. They may have gone extinct 66 million years ago, but in the scientific literature, they’re still flying high. Reporting in the journal Current Biology, a team led by David Hone (Queen Mary University of London) recently described a new Jurassic pterosaur found in 147-million-year-old sediments in Germany that they’ve dubbed Skiphosoura bavarica. The specimen is preserved in exquisite 3-dimensional detail. With a seven-foot wing span, it’s described as something of a “mid-sized” pterosaur, one that seems to fill an evolutionary gap between early, smaller pterosaurs and giants that would evolve later. Along with Skye McDavid (Lauer Foundation for Paleontology, Science, & Education), Hone has also clarified a mystery regarding a pterosaur with a wing span of six feet discovered over…

If you’d been asked just a couple months ago, “How many moons circle Saturn,” you would have confidently answered, “Why, 146, of course!” Well, try 274! That’s the astounding new number determined by Edward Ashton (Academia Sinica Institute of Astronomy & Astrophysics, Taiwan) and colleagues in Research Notes of the American Astronomical Society. They discovered the new moons using the Canada-France-Hawaii Telescope at Maunakea. But are they really moons? Well, yes, in the traditional sense of any object circling a planet in a consistent, trackable orbit. But should that definition be changed? Many of Saturn’s new moons are tiny—a few miles in diameter. Some have strangely angled orbits. And many travel around Saturn in the opposite direction of the planet’s more well-known major moons. Many are believed to be fragments…

The eucalyptus tree is an icon of Australia. It relieves human coughs and feeds the lovable koala and it serves as a home and/or food source for some 20,000 insect species. All those insects leave clear marks on leaves from such activities as chewing, mining, galling and piercing. They’ve been doing so for a long time across a broad expanse. As described in New Phytologist, a team led by L. Alejandro Giraldo (Pennsylvania State University) examined 52-million-year-old fossilized eucalyptus leaves from Laguna del Hunco in Argentinian Patagonia and identified clear signs of 28 types of leaf damage related to insects. They compared these to contemporary eucalyptus leaves from Australia kept in herbariums. Lo and behold, there was a precise match to the 28 types of leaf damage seen in the…

Ancient asteroids hold all the right organic compounds for life, and those same compounds were likely present on early planet Earth—or delivered here by impacting asteroids. Some have theorized such compounds were “jolted alive” into life’s building blocks by lightning strikes. Others poo-poo that idea, noting that lightning strikes are ephemeral—few and far between—and any life started by a strike would not likely have lasted long nor spread far. Now, a research team suggests a widespread and sustained source of electricity that could have tickled life’s building blocks. In the journal Science Advances, a team of Stanford University chemists led by Yifan Meng suggests “microlightning” might have been a prime driver. They note fine sprays of water generate tiny electrical discharges all the time from events as common and frequent…

Alaska is home to over 130 volcanoes, 90 of which have been active in the last 10,000 years and more than 50 that have been active since 1760. Current volcanic activity may make headlines before you can read this article, as craters smolder and earthquakes shake residents daily in the northern reaches of the Pacific Ring of Fire. The Aleutian Islands and the panhandle of Alaska are rich in geology, geography and history. Let’s explore how past volcanic eruptions, earthquakes, tsunamis and a world war have rocked Alaskan residents and enticed travelers to visit this scenic land with an explosive past, present and future. HISTORY—LAND BRIDGE TO STATEHOOD One theory as to how North America became populated with humans goes back to 1590 and the possibility of a land bridge…

Emerald is the green variety of beryl, colored by trace amounts of chromium and sometimes also vanadium. With a hardness of 7.5 to 8 on the Mohs scale, it is relatively durable but often contains internal fractures or inclusions known as “jardin” (French for garden). These inclusions are considered part of the gem’s natural character. Its striking green hue has made it one of the most prized gemstones throughout human history. How Emerald Is Formed Emeralds develop in hydrothermal veins or pegmatites where beryllium-rich fluids interact with chromium-bearing host rocks, usually schist, limestone or granite. The necessary mix of elements is rare, making emeralds one of the least common gemstones. Their formation requires both specific chemistry and slow cooling over millions of years. High-quality emeralds must contain Cr³+ — some…

There’s an old saying that finding fossils in Oregon is not about where to look, but where not to look. The Oregon Coast and much of the Coast Range was underwater and part of an ancient sea floor. So, marine fossils can be found a significant distance inland from the current shoreline. There are numerous geological formations here and each one holds different specifics and clues about what used to call this place home. Today, Oregon Coast fossils are mostly known from three formations: Astoria, Nye Mudstone and Coaledo. Astoria is roughly 15- to 20-million-year-old blue-grey sandstone layers mixed with compressed volcanic ash, making up the northern to central coast beaches. Nye Mudstone is up to 20-million-year-old, fine-grained grey sedimentary rock found in areas within the central coast. Coaledo is…

As long as there’s been life on Earth, there has been extinction. Species come and species go, but at certain periods an inordinate number of creatures and plants have gone extinct seemingly all at once. Ask any three paleontologists what causes such mass extinction events, and you’ll get three different answers—and maybe start a fistfight! Now, though, we may be narrowing it down. Scientific American senior editor Clara Moskowitz reported on the “Big Five” extinction events that catch everyone’s attention. That’s because each time, at least 70% of species on Earth vanished. These took place during the Ordovician/Silurian transition, the Late Devonian, and during transitions between the Permian/Triassic, Triassic/Jurassic and Cretaceous/Paleogene periods. For each event, Rick Simonson and David Bond (University of Hull) prepared nifty graphs showing nearly 20 likely…

Earth has been described as a layered onion with an inner core, an outer core, a mantle and a crust. The crust moves about in a highly dynamic manner as plates diverge, converge or slide past one another. The hot-hot liquid outer core is similarly dynamic as it helps drive our planet’s magnetic field while sloshing around the hard inner core. But that middle mantle region has been described by some as “boring” and “like a superslow lava lamp.” But no longer! In the journal Science, reporter Paul Voosen (who noted that lava lamp analogy) reported on several academic articles and presentations that suggest far more complexity for our middle Earth. For instance, rather than one big more-or-less uniform pile of mush, with something of a mineral transition zone 660…

Recent times have seen severe drought conditions and increased reliance on groundwater aquifers to draw fresh water to meet the needs of ever-expanding populations. But how easily are aquifers recharged? Conventional methods of measuring and assessing the state of aquifers using monitoring wells have proved limited, but new techniques are emerging to better assess groundwater storage across space and time and to peer ever deeper underground. Writing in the journal Science, a team of earth scientists and geophysicists led by Shujuan Mao (Stanford University) used seismic sensing (specifically “seismic ambient-field interferometry”) to gain a more accurate sense of how groundwater beneath Los Angeles ebbed and flowed over two decades and how it responded when a historic drought was broken by a historic wet season in 2023. While this rainy season…

Earth is estimated to be 4.543 billion years old, and it’s believed our Moon was born from a violent collision between the newly formed Earth and another young Mars-sized protoplanet dubbed Theia not long thereafter. But how long was “not long?” Until recently, the estimated age of lunar formation was 4.35 billion years ago, and folks who cling to that age are considered “young-Moon” advocates. In the pages of the journal Science, journalist Paul Voosen describes new research on old Apollo-era rocks suggesting that the Moon-forming impact occurred earlier. In recent years, scientists have studied the decay of uranium to lead within zircon crystals, the decay of hafnium to a light tungsten isotope, and the decay of rubidium to strontium, all from specimens brought back to Earth courtesy of NASA’s…

An interesting and accessible locality for starburst quartz crystals is on a steep hillside just east of Water Street in the mountains north of Kingston, New Mexico. The quartz crystals formed in a Tertiary quartz monzonite porphyry that intruded Pennsylvanian-Permian sedimentary rocks. The crystals formed in veins and vugs in silicified rocks of the porphyry. Many of the quartz crystals form a radiating “starburst” pattern with excellent terminations. The crystals are generally small and less than a half-inch long but are abundant and often occur in aggregates of hundreds of crystals. The crystals are milky white to nearly clear. Most forms of quartz are common and of little interest to anyone, but good crystals are rare and can be of great interest to both collectors and lay people. You do…

What do emerald, coal, marble, galena, agate and serpentinite have in common? Geologically and mineralogically speaking, not much. Yet all share membership in a rather elite club composed of “geosymbols”—mineral materials that legislators have formally designated as their states’ official rocks, minerals and gemstones. Every state except North Dakota has at least one geosymbol. Nineteen states have two geosymbols, while fifteen have three. Among the better-known geosymbols are California gold, Missouri galena and Arizona turquoise. Lesser-known geosymbols include Delaware sillimanite, Oregon awaruite and Rhode Island bowenite. Considered collectively, the list of 97 state rocks, minerals and gemstones paints an interesting cultural, historical, mineralogical and economic picture of their respective states and of the nation as a whole. A GEOSYMBOL HISTORY State symbols, beginning with flowers, first appeared in the 1890s.…

Gold has long been revered for its beauty, rarity and versatility. Throughout history, it has symbolized wealth and served as currency, but in the realm of jewelry making, gold is more than just a precious metal—it’s a science. Over the years, jewelers have learned to manipulate gold’s inherent properties to suit specific needs. Here are the different types of gold alloys, how they’re used and the important factors to consider when working with gold in your jewelry creations. Gold in its natural form is a soft, yellow metal that’s easy to shape and manipulate. However, as beautiful as pure gold is, it’s not practical for most jewelry applications because it lacks the durability needed for everyday wear. To overcome this, gold is often alloyed with other metals, which enhances its…

It seems like plain old common sense. Increase the complexity and diversity of topography and you’ll increase biodiversity. But now we have strong data to support that hypothesis. Writing in the journal Science, a team of earth and evolutionary scientists led by Eyal Marder (Indiana University, Bloomington) detailed how increased diversity of small animal populations is directly correlated with tectonic uplift. The greater the rate and magnitude of such uplift, the greater the range of potential territories for critters of diverse sorts to colonize, from high mountain peaks to foothills, meandering valleys and depositional lowlands. As mountains grow, each of these resulting realms provides new niches for varied species. The high mountains also separate and isolate populations, further facilitating the development of new species. In addition to running “coupled landscape-biological…

The biomolecules fueling life on Earth are heavily dependent on phosphorus. In fact, phosphates are said to be the second-most abundant mineral in the human body. Phosphorus is present in every cell and a key component of bones and teeth. There’s just one problem: “the phosphorus problem.” This element is not all that common in watery environments where most scientists believe life began. But is that problem now solved? Robert Service, a reporter for the journal Science, summarizes several new research findings in journals such as Communications Earth & Environment, Proceedings of the National Academy of Sciences, Geochimica et Cosmochimica Acta, and Science Advances. These studies show that volcanic lavas yield phosphorus, and early Earth was nothing if not rich in volcanic lavas. It’s suggested that volcanic activity around hot…

What was the fur color of a 160-million-year-old mammal? In the past, paleoartists had to guess. It was left to artistic license and artists often used contemporary animals to fill their palettes, sometimes painting bright colors and stripes. Now, superbly preserved “mammaliaform” fossils are edging out artistic license and providing a scientific look at ancient mammal fur. The fossils—a total of six Jurassic and Cretaceous mammals from northeastern China—show halos of fur around the bones. As described in the journal Science, a team led by Ruoshuang Li (China University of Geosciences) and Matthew Shawkey (University of Ghent, Belgium) took a close look at that fur. Within it, they found structures known as melanosomes that hint at color. They compared what they saw in the fossils with melanosome morphology in 116…

Scientists estimate the age of Earth at 4.543 billion years. During that long span, our planet has constantly been pelted by visitors from space: asteroids, comets, meteors and even a hypothetical Mars-sized proto-planet. But for much of our planet’s early history, its surface was a sea of molten magma, so the earliest impactors left no trace. The oldest definitive impact crater has been Australia’s Yarrabubba dated at 2.23 billion years old. Now, there’s one older. Writing in the journal Nature Communications, a team led by Christopher Kirkland (Curtin University, Australia) presents evidence of a 3.47 billion-year-old crater some have dubbed the North Pole Crater or the Pilbara Crater north of Yarrabubba. Evidence includes shocked rocks in the form of shatter cones that are unequivocal evidence of an immense strike from…

By day, Julia DeLo works as an engineer in the aerospace industry and by night, she pursues her passion for cutting gemstones, applying her analytical and mechanical skills to optimize and simplify designs. Julia’s goal with Sunset Pear was to provide cutters with a well-performing pear that doesn’t require numerous tiers and facets. This allows for a faster-cutting gem from rough that lends itself to a pear shape. For this, I used a beautiful deep orangey-red Malawi garnet as a nod to the design’s moniker. Ultimately, the garnet was a little darker than expected, but this design is optimized for R.I. of 1.6-1.7 and up. After my initial preform, I started cutting this stone with an Impulse 500 lap. This is a new-to-the-market hybrid bond lap that leaves a smooth…

Flint has often been used throughout history and is thought to be as old as 160 million years. It was a prime natural resource for tool manufacturing in the past. However, in a few deposits near the city of Ostrowiec Świętokrzyski, a type of flint that has a banded, layered appearance was found. As named by its locale, Polish flint, also known as striped or banded flint, has since become a valuable addition to any lapidary artist’s arsenal for its stunning layered, often concentric banding formed by precipitated silica. This material is ideal for all types of jewelry due to its exceptional Mohs hardness of 6.5 to 7 and its interchanging cream and brown coloring. WHERE TO FIND POLISH FLINT Finding Polish flint in the marketplace online or at shows…

You can’t fake a real connection — and you sure can’t force five women to dig side-by-side through dirt, sweat and storms unless something powerful is holding them together. The Mineral Missfits didn’t just find crystals deep in the Earth; they found each other and became leaders in the rockhound world. One is the President and founder of the East Coast Gem and Mineral Society, another is a founder and prior owner of a Herkimer diamond mine in Sprakers, New York. She creates Facebook reels twice a day with 314,000 viewers. The other three women are also rockhound souls - an accountant, a veterinarian and an army veteran. What started at a Herkimer diamond mine turned into a bond tougher than bedrock and brighter than any stone they ever pulled…

At wine tastings today you’re likely to find “flinty” sauvignon blancs, “chalky” Rieslings, and syrahs that “express the essence of limestone soil.” You’ll also notice winery names like Basalt, Rhyolite, Syncline and Alluvium, along with labels that attribute certain wine tastes to “gray-blue Devonian slate” or “200-million-year-old Jurassic soil.” But you haven’t mistakenly wandered into happy hour at a geologists’ convention, you’re just seeing firsthand the impact of geology in viticulture and on the controversial wine-tasting topic of minerality. THE WINE-SOIL CONNECTION The Christian monks who launched France’s first big winemaking effort in the Middle Ages realized that grapevines thrived at some locations but not at others. Legend says they determined the best sites for planting by tasting the soil—which made sense at a time when grapes were thought to…