Indholdsfortegnelse for June 2025 i Rock and Gem

For a while, it was an on-going news flash: Earth could very well suffer a hit sometime in 2032 by a “city-killer” asteroid zeroing in on our part of the solar system, an asteroid with a diameter of 130-300 feet. (For some context, the Chicxulub impactor that took out the dinosaurs had an estimated diameter of 6.2 miles.) The space visitor in question, designated asteroid 2024 YR4, was initially given the highest probability ever for a major Earth impact by a large object: 3.1%. That may seem low, but apparently in the world of probability, it’s fairly high. But no sooner was that risk announced with somber nods than it immediately began to decline. First from 3.1% to 1.5%, then lower still. Within days, most earth and planetary scientists merely…

The race to the Moon is on, and it’s no longer between nation states. Private companies are jumping in. Recently, one company sang sweet success while another moaned dreadful sorrows. On March 2, Firefly Aerospace became the first to brag of a successful, no-hitch commercial landing on the lunar surface. While others beat them there in the past couple years, they’ve either crash-landed or landed then toppled over. But Blue Ghost M1 set down on a volcanic plain and immediately began sampling and analyzing soil, deploying a heat probe, and checking the Moon’s magnetic field. As a little bonus, during the full lunar eclipse in the wee morning hours of March 14, it transmitted what, to it, was a full solar eclipse as Earth swung between the Moon and the…

Along England’s southwest edge resides Mary Anning’s “Jurassic Coast,” a World Heritage Site with ammonites and sea monsters known to fossil fanatics far beyond English shores. Less well known but equally impressive is a parallel universe yielding similar fossils along England’s far northeast Yorkshire region. Referred to as the “Dinosaur Coast,” it’s centered at the seaside port of Whitby, which hosts treasures well beyond fossils for a trip you’ll long remember. EXPOSING THE JURASSIC Rocks exposed along the Yorkshire coast span almost the entirety of the Jurassic Period, which falls smack in the middle of the Mesozoic Era, or the Age of Dinosaurs. Exposed sediments of the Redcar Formation were laid down 195 million years ago. Subsequent layers piled on top provide an unbroken record spanning the next 60 million…

Magnetite (Fe3O4) is a naturally magnetic iron oxide mineral. It is black to dark gray with a metallic luster and forms in octahedral crystals or fine grains. Because of its strong magnetism, it is easily separated from other minerals. How Magnetite Forms Magnetite crystallizes in igneous, metamorphic and sedimentary environments. In igneous rocks, it is found in basalt and gabbro where it forms from cooling magma. Metamorphic magnetite forms when iron-bearing minerals are altered under heat and pressure. In sedimentary environments, it is best known in coastal areas as black sand. As rocks weather and break down, water and wind transport heavy magnetite grains, concentrating them along shorelines. Some animals, including birds, salmon, bees and sharks, contain magnetite in their bodies, which helps them sense Earth’s magnetic field for navigation…

Along with Murano glass, limoncello and handmade pasta, precious red coral is among the iconic products of Italy. Known as “red gold” and the “ruby of the sea,” precious red coral is valued for its saturated red color, lustrous polish, unusual marine origin, and rich lore that predates Roman times. And the qualifier “precious” is not pretentious: Today, a single pound of top-grade, rough red coral as taken from the sea sells for about $3,000. But while red coral has a long and colorful past, its future is uncertain. Overharvesting has depleted many red coral colonies to the extent that the polyp that produces red coral has become an endangered species. Although many regulations now protect the Mediterranean’s red coral beds, illegal harvesting remains a threat. Compounding this problem is…

Forget the Stone Age. Try the Bone Age! A new discovery suggests Homo erectus used bone as material to craft tools one million years earlier than thought. While it’s likely they may have always used bone, we now know for certain that they actively broke and manipulated bone to craft tools as far back as 1.5 million years ago. Writing in the journal Nature, a team led by Ignacio de la Torre (Spanish National Research Council) describes bone tools shaped by knapping at the famous Olduvai Gorge in Tanzania. They were found in what appears to be a hippo butchery site in a well-dated stratigraphic horizon. The tools came from bones of bovines, hippos, and elephants. The date of this locality, which yielded 27 confirmed bone artifacts, pushes the systematic…

As reported in the journal Science, Politico, and elsewhere, the United States Geological Survey soon will have a new head: most likely Ned Mamula, who has been nominated by the Trump administration. With a Ph.D. in Petroleum Geology & Geophysics from Texas A&M and a Master’s degree in Strategic Studies & Resource Policy from Johns Hopkins University School of Advanced International Studies, Mamula boasts strong academic credentials along with 30 years of government and managerial experience that has seen bipartisan support. For instance, his past jobs include serving as a staff scientist with the USGS and as director of the Department of Energy’s critical minerals program under both Donald Trump’s first administration and that of Joe Biden. If confirmed, Mamula likely will work to revive mining for critical minerals within…

The Paleontological Research Institution’s (PRI) Museum of the Earth resides in Ithaca, New York, where it’s been since its founding in 1932. As I myself saw during a visit some 15 years ago, it’s one fantastic repository brimming with 7 million specimens. In fact, it houses one of the world’s greatest invertebrate fossil collections. Now, facing severe financial constraints, it may shutter. The Museum of the Earth is a nonprofit that relies largely on donations to maintain operations. Per a PRI press release, several long-time loyal and extremely generous philanthropic donors have faced financial hardships themselves and are unable fulfill pledges amounting to several million dollars. The museum quickly needs $2 million to $3 million to avoid defaulting on the mortgage. PRI has already streamlined operations, paused some programs, laid…

Beachcombers know that only certain species of oysters produce pearls. No less coveted for their rarity by rock hunters are the speleological treasures known as “cave pearls.” These natural prizes are nestled like their namesake into the subterranean origin stories of geologic marvels like Wisconsin’s Cave of the Mounds and Yemen’s Well of Hell, where its precious cache is guarded (so legend goes) by folkloric jinn. What is a cave pearl? Simply put, cave pearls are concretions of calcium salts that, like oysters, form concentric layers around an irritant-inducing nucleus, according to David Bunnell, writing for the largest caving-focused membership organization in the world, the National Speleological Society (NSS). These subterranean cousins to stalactites and stalagmites are found in limestone caves and pools. They form when water, dripping into a…

Astrophyllite is found in several locations around the world, but most notably in the Khibiny Massif region of the Kola Peninsula of Russia. This eye-catching stone contains all sorts of minerals, including potassium, iron and manganese. It can create some one-of-a-kind cabochons using its natural, flashy exterior. Depending on the composition of minerals present, it can take on a light or dark appearance featuring embedded eye-catching golden leaves. Its name comes from the Greek words “astron,” meaning “star,” and “phyllon,” meaning “leaf.” Astrophyllite earned this name because of its appealing dark amber to golden bronze when angled against the light. WHERE TO PURCHASE While it’s considerably rare, it’s not uncommon. It can be found at shows and online marketplaces. Use your best judgment picking out useable pieces. Oftentimes, I see…

In the classic James Bond movie On Her Majesty’s Secret Service, the intrepid British secret agent, when asked where he intends to spend his two-week leave, laconically replies, “Just some place to laze about. Beachcombing.” That beachcombing would appeal even to the worldly James Bond speaks volumes about its universal popularity. Although defined simply as searching beaches for things of value, interest, or utility, beachcombing is actually an appealing mix of serenity and adventure. It offers peace, quiet, a respite from life’s routines and a connection with nature, all backed by the tantalizing possibility of finding something beautiful, unique or valuable. Although beachcombing today is synonymous with leisure, relaxation and recreation, its origins were far different. THE BEGINNING The word “beachcomber” initially referred to the long, rolling waves that swept,…

In previous articles, I’ve reported on the biotech company Colossal Biosciences and its ongoing efforts to bring back the woolly mammoth—or, at least, a woolly mammoth look-alike—by genetically engineering and modifying an Asian elephant. They’re now one step closer to their goal with a critter that, according to stereotype, would terrify an elephant. Say hello to the woolly mouse! Taking ordinary lab mice, the Colossal Biosciences team edited genes for shaggy fur to make them similar to such genes found in frozen mammoths, thus crafting a new mouse species that would be well adapted for life in the cold of an Ice Age. According to photos in a preprint of an article on bioRxiv by Rui Chen (Colossal Biosciences) and team, the little critter sure is a lot cuter than…

The bone is incomplete and tiny: two inches long and thin as cardstock. It’s a wonder it fossilized at all! And the puncture is even tinier: a mere sixth of an inch wide. Yet this tiny trace on a fragment of bone may tell of a mighty struggle at river’s edge. Writing with colleagues in the Journal of Paleontology, Caleb Brown (Royal Tyrrell Museum of Paleontology) provides a close look at a pterosaur neck bone plucked from 76 million year old Cretaceous strata in Canada’s Dinosaur Provincial Park. Pterosaurs are believed to have skimmed waters, dipping down to snatch a fish for dinner. Crocodilians lived in such waters, and today’s crocs are notorious ambush predators. Brown suggests two possible scenarios: either the pterosaur alighted at water’s edge and was snatched…

Truly ancient rocks are rare on Earth’s surface. The planet may be 4.5 billion years old, but it’s a dynamic planet with plate tectonics that constantly reshape things. Thus, we’re lucky to find rocks 3-4 billion years old that can be accurately dated. They are there, but at just a handful of spots in Canada, Greenland, Australia and Africa. Now, one spot is officially off-limits. Per an article in the journal Science by freelance science writer Rachel Berkowitz, rocks dated at 3.8 billion years old reside on tribal lands of the Inukjuak in the far northern reaches of Canada called the Nuvvuagittuq Greenstone Belt. Tribal leaders have allowed geologists access to their lands and have assisted them in research expeditions. But in recent years, folks posing as museum curators went…

Labradorite is a variety of plagioclase feldspar that is dark gray to black in ordinary or low light, but it often has a brilliant play of colors when the right surfaces are exposed to sunlight. These colors result from a type of iridescence that occurs in labradorite feldspar, so it is often referred to as labradorescence. The colors can be vibrant and include blue, green and gold, and the colors shift as the mineral is moved. Labradorite with good color, also known as schiller, is a highly desirable gemstone. MINERALOGY Feldspars make up nearly 60% of the Earth’s crust and are important rock-forming minerals. Virtually all rocks, except for carbonates and other precipitate rocks, have some percentage of feldspar. Feldspars are silicate minerals, and they are primarily silicon, oxygen, aluminum,…

Faceted pearls are delightful to admire. They’re unexpected and not a traditional material that people think to facet. Visually, the pearl looks like it has curved, pillowy facets and unlike other materials, you aren’t focused on light return. For pearls, you’re focused on adding some geometric patterns and intrigue to your piece. Michael Holmes’ Sparrows Pearl is a delightful challenge focused on maximizing interest and keeping you on your toes. PEARLS - WHAT ARE WE CUTTING? The layers of color on a pearl are called nacre. In cultured pearls, nacre grows around a pearl-starter known as the nucleus. In Tucson, I visited Wu’s Original Tradings, Inc., a pearl dealer from Houston, Texas. Mr. Wu stressed the importance of faceting a pearl with thick nacre; otherwise, you will be cutting into…

White Sands National Park, known for its beautiful white gypsum sand dunes, is surrounded by government facilities that were instrumental in testing the first atomic bomb and the development of the U.S. Space Program. This New Mexico dune field is the largest of its kind on earth, covering 275 square miles, an average of 30 feet deep with dunes reaching up to 60 feet high, at an elevation ranging from 3,887 to 4,116 feet above sea level. Gypsum is a sulfate mineral composed of calcium sulfate dihydrate. It typically forms in translucent crystals of selenite. It has a Mohs hardness value of 2 and is water-soluble, less so at higher temperatures and rarely found as sand…so why here in the Tularosa Basin in south-central New Mexico—an area so large and…

Petoskey stones are a prized find along the shores of Lake Michigan. To paleontologists, however, they remain simply Hexagonaria coral until they are cut, polished and often sold for a hefty price. Only then do they earn the name “Petoskey Stone.” BEAUTIFUL PETOSKEY STONES Walking along the northern Lower Peninsula shorelines of Lake Huron and Lake Michigan, it is easy to see this fossil’s natural attraction for people. Looking into the water, one can sometimes see this coral, rounded by relentless waves, worn smooth and showing its beautiful internal structure. Once removed from the water, however, it quickly dries and loses its bright polished shine. To achieve that permanent shine, it is necessary to polish the rock by grinding and sanding it and finishing it with a polishing compound to…