Bearded Geology

In celebration of winter weather (or disdain of it, your choice), I thought I'd do a brief post on beds, but not the geological kind. This post is mainly in response to a bedsheet set made by Cannon that I own. The following image is a photograph of the snowflake pattern on my bed sheets. For those of you who have taken a mineralogy class (especially my mineralogy labs), what kind of rotational symmetry do you see in the three different snowflake patterns? I see five-fold, six-fold, and eight-fold rotational symmetry: In crystallography, there are only five rotational symmetry patterns: one-fold, two-fold, three-fold (triangular), four-fold (square), and six-fold (hexagonal). You can repeat patterns with these symmetries across a two-dimensional plane in some arrangement to fill the entire plane. Five-fold, seven-fold, and anything higher is forbidden in classical symmetry; you cannot repeat these patterns in any arrangement without leaving gaps between the pattern.  In the above i...

Although the pandemic left me at home for much of the year, I haven't posted much throughout this year. But, I have recently been working on two ongoing projects that I've added to the blog and are accessible at the top of the home page via the new "Projects" link. These are the World's Largest Crystals and the World's Largest Gemstones . Two databases of the largest known crystals and gems.  I've long been wanting to work on an update to Peter Rickwood's 1981 publication, The Largest Crystals , in which Rickwood painstakingly compiles information about the world's largest known crystals using sources such as eyewitness testimonies and 19th century publications. The introduction to Rickwood's paper is a great starting point to understand what the largest crystals are, how we can define them, and what complications can arise in determining them as the largest. Most of the minerals that he describes are included in the World's Largest Crysta...

Since the COVID-19 pandemic, many classes have been forced to adapt to online teaching. I myself am adapting some mineralogy lab materials to online and found that this blog can provide a platform for supplemental material. This includes a new page in the Mineralogy Course Links page: " Bearded Geology's 3D Crystal System Model " page.  This new page includes interactive 3D models of the six crystal systems (sorry, trigonal). These are designed to provide interactive examples of the rotational axes and mirror planes in these crystal systems when the infamous wood block models are not available.  All but two models were designed by me using Microsoft Paint3D, and all rotational axes and mirror planes were added by me as well. The tetragonal model is from Microsoft's 3D Library and the triclinic model is modified from the SketchUp 3D library. Next to each model, I've included a link to download each of them in .GLB format for personal or educational use on their own...

Gemstones are inherently in demand, and as such, there are many who attempt to either create an imitation (simulant) gemstone or create a lab-grown (synthetic) gemstone. Simulant gemstones are those that mimic another, but have different properties and compositions than the imitated gem, such as a red-dyed quartz simulating a ruby (a variety of corundum) ( read more here about simulants ). Whereas, synthetic gemstones are those that have the same chemical composition and properties as the imitated gem ( read more here about synthetics ). Synthetic gemstones are not a new concept; rubies have been known to be synthesized since the late 19th century and emeralds (a variety of beryl) since the 1930s. Undoubtedly many antique jewelry items bear synthetic gems such as ruby and emerald, and as technology and techniques advance, more and more gems are becoming replicated. Real rhodochrosite cabochons (two on the left) and imitated rhodochrosite (two on the right). The banding of the simu...

Looking through the department's collection for the most difficult rock and mineral samples to put on the lab exam... Happy Finals Week!!

Various types of micrometeorites (credit: ©  Jon Larsen ) In 1970, a machine was rigged onto a high-altitude atmospheric balloon and sent 21.7 miles (35 km) into the sky over Texas. The machine, lovingly named the Vacuum Monster after a creature in The Beatles' Yellow Submarine  movie, collected microscopic particles as small as two micrometers (microns) in diameter. Some of which were determined to be extraterrestrial, marking this as the first time "space dust", or more precisely, micrometeorites, were collected at altitude. Micrometeorites are a niche area of study within astrogeology (the study of the geology of extraterrestrial bodies), but has recently been expanding as it is now more accessible for researchers. On a large scale, international space agencies have devoted funding for missions to collect material directly from asteroids and comets, such as the ongoing  Hayabusa 2  mission to the asteroid  Ryugu , which has very recently completed its ...

The MOOOOOOOOON!!! (image: Wikimedia ) 50 years ago today, Apollo 11 accomplished the bold feat of landing on the Moon and not only did they walk on the Moon, they brought back some of it with them on their return for study. Some bits of lunar rock found their way to becoming thin sections, which you can view here , and occasionally get loaned out to researchers outside of NASA. I was lucky enough to handle and view some of these thin sections in my undergrad Igneous and Metamorphic Petrology class, as well as a thin section of a Martian meteorite (the closest I'll ever get to being on Mars). The lunar rocks have been well-studied by geologists over the years and Mindat.org has curated a list of minerals found on the moon, almost all of which are also found on Earth. The Moon can, in a broad sense, been generalized into two types of igneous rocks: basalt and anorthosite. The bright, white-grey parts of the Moon are the anorthosite dominated areas. These are feldspar-rich ro...

While researching dolomite, I read this delightful bit in the journal AAPG Bulletin : "Furthermore, the feasibility of this, or a similar system was recently demonstrated (unintentionally) by a male dalmatian who produced uroliths [essentially kidney stones of the bladder] of ordered dolomite in his urinary bladder." That is a sentence that I never thought I would read in a highly respected geologic research journal. Previously, I would have thought that a dalmatian would exclusively be a subject in either a medical or biological study, not a geological study. I stand corrected. This also raises a series of questions: (1) Was this the author's dalmatian? If not, who's dog was this? (2) What provoked a geologist to look at the uroliths, especially if it was from someone else's dog? (3) How did someone find the stones? Did someone wait for the uroliths to pass, did someone dig around outside (or inside!) in a puddle of pee, or were they retrieved via surg...

    Another periodic mineral post! Since the last one was realgar, an arsenic bearing mineral, I thought I'd continue the theme of toxic minerals with galena. Galena is a very dense lead sulfide mineral (the chemical formula is PbS) and is the primary ore mineral that is mined for lead. Typically associated with zinc minerals such as sphalerite (ZnS), lead has long been mined in the US since the colonial period, but today there are only  ten mines in the US that currently produce lead . Five of these are in Missouri (the Brushy Creek, Buick, Fletcher, Sweetwater, and Viburnum mines), two in Alaska (the Greens Creek and Red Dog mines), two in Idaho (the Galena and Lucky Friday mines), and one in Washington (the Pend Oreille mine). Although, there has been recent discussion in late 2018 to re-open the Bunker Hill Mine in Idaho. However, the Bunker Hill Mine is next door to the second-largest EPA Superfund site which houses the Bunker Hill smelter complex and tailing piles...

Geologists frequently use the term dolomite to describe both the mineral and the carbonate rock that is comprised of that same mineral. However, I find this to be unnecessarily confusing, especially since a clear distinction between calcite and limestone is recognized. So, I've dug up some history to the term dolomite . In 1768, Swedish natural scientist and “father of modern taxonomy”, Carl Linnaeus (later known as Carl von Linné), briefly described a type of rock he called marmor tardum , translated as slow marble . Marmor tardum , Linnaeus says, is a white marble that is as hard as quartz, but slowly effervesces potentially describing a dolomitized marble. Italian geologist, Giovanni Arduino, also described a marble in 1779 that has been considered to be dolomitized. However, it wasn’t until 1791 that a more complete description of dolomite was published by French geologist Déodat Gratet de Dolomieu, who described dolostones in the Alps (a region then called County Tyrol) ...

Realgar (red) with quartz and pyrite. I was thinking of periodically posting about some particular mineral, fossil, or rock (particularly when I don't have a topic to discuss), and I thought that realgar would make for a good mineral to discuss. Realgar is an arsenic sulfide mineral with the best chemical formula I've ever seen: AsS (sometimes written As 4 S 4 ). It's very soft ( hardness 1.5-2 ) with a brilliant red color and a resinous, greasy luster  and is associated with hydrothermal ore deposits. Several fantastic specimens of realgar come from Paloma, Peru (such as the one pictured). Interestingly, realgar reacts to sunlight. I don't understand exactly how this happens, but given some time in sunlight, it will alter to a yellow-orange mineral called pararealgar. So, if you collect a sample of realgar, keep it in a dark box or drawer. I didn't know about this when I got my sample (pictured), but I've been fortunate to not have enough space to displa...