2025-12-05 00:30:04
One of the major difficulties in studying electricity, especially when compared to many other physical phenomena, is that it cannot be observed directly by human senses. We can manipulate it to perform various tasks and see its effects indirectly, like the ionized channels formed during lightning strikes or the resistive heating of objects, but its underlying behavior is largely hidden from view. Even mathematical descriptions can quickly become complex and counter-intuitive, obscured behind layers of math and theory. Still, [lcamtuf] has made some strides in demystifying aspects of electricity in this introduction to analog filters.
The discussion on analog filters looks at a few straightforward examples first. Starting with an resistor-capacitor (RC) filter, [lcamtuf] explains it by breaking its behavior down into steps of how the circuit behaves over time. Starting with a DC source and no load, and then removing the resistor to show just the behavior of a capacitor, shows the basics of this circuit from various perspectives. From there it moves into how it behaves when exposed to a sine wave instead of a DC source, which is key to understanding its behavior in arbitrary analog environments such as those involved in audio applications.
There’s some math underlying all of these explanations, of course, but it’s not overwhelming like a third-year electrical engineering course might be. For anyone looking to get into signal processing or even just building a really nice set of speakers for their home theater, this is an excellent primer. We’ve seen some other demonstrations of filtering data as well, like this one which demonstrates basic filtering using a microcontroller.
2025-12-04 23:00:08
The past few months, we’ve been giving you a quick rundown of the various ways ores form underground; now the time has come to bring that surface-level understanding to surface-level processes.
Strictly speaking, we’ve already seen one: sulfide melt deposits are associated with flood basalts and meteorite impacts, which absolutely are happening on-surface. They’re totally an igneous process, though, and so were presented in the article on magmatic ore processes.
For the most part, you can think of the various hydrothermal ore formation processes as being metamorphic in nature. That is, the fluids are causing alteration to existing rock formations; this is especially true of skarns.
There’s a third leg to that rock tripod, though: igneous, metamorphic, and sedimentary. Are there sedimentary rocks that happen to be ores? You betcha! In fact, one sedimentary process holds the most valuable ores on Earth– and as usual, it’s not likely to be restricted to this planet alone.
We’re talking about placer deposits, which means we’re talking about gold. In dollar value, gold’s great expense means that these deposits are amongst the most valuable on Earth– and nearly half of the world’s gold has come out of just one of them. Gold isn’t the only mineral that can be concentrated in placer deposits, to be clear; it’s just the one everyone cares about these days, because, well, have you seen the spot price lately?
Since we’re talking about sediments, as you might guess, this is a secondary process: the gold has to already be emplaced by one of the hydrothermal ore processes. Then the usual erosion happens: wind and water breaks down the rock, and gold gets swept downhill along with all the other little bits of rock on their way to becoming sediments. Gold, however, is much denser than silicate rocks. That’s the key here: any denser material is naturally going to be sorted out in a flow of grains. To be specific, empirical data shows that anything denser than 2.87 g/cm3 can be concentrated in a placer deposit. That would qualify a lot of the sulfide minerals the hydrothermal processes like to throw up, but unfortunately sulfides tend to be both too soft and too chemically unstable to hold up to the weathering to form placer deposits, at least on Earth since cyanobacteria polluted the atmosphere with O2.
One form of erosion is from wind, which tends to be important in dry regions – particularly the deserts of Australia and the Western USA. Wind erosion can also create placer deposits, which get called “aeolian placers”. The mechanism is fairly straightforward: lighter grains of sand are going to blow further, concentrating the heavy stuff on one side of a dune or closer to the original source rock. Given the annual global dust storms, aeolian placers may come up quite often on Mars, but the thin atmosphere might make this process less likely than you’d think.
We’ve also seen rockslides on Mars, and material moving in this matter is subject to the same physics. In a flow of grains, you’re going to have buoyancy and the heavy stuff is going to fall to the bottom and stop sooner. If the lighter material is further carried away by wind or water, we call the resulting pile of useful, heavy rock an effluvial placer deposit.
Still, on this planet at least it’s usually water doing the moving of sediments, and it’s water that’s doing the sortition. Heavy grains fall out of suspension in water more easily. This tends to happen wherever flow is disrupted: at the base of a waterfall, at a river bend, or where a river empties into a lake or the ocean. Any old Klondike or California prospector would know that that’s where you’re going to go panning for gold, but you probably wouldn’t catch a 49er calling it an “Alluvial placer deposit”. Panning itself is using the exact same physics– that’s why it, along with the fancy modern sluices people use with powered pumps, are called “placer mining”. Mars’s dry river beds may be replete with alluvial placers; so might the deltas on Titan, though on a world where water is part of the bedrock, the cryo-mineralogy would be very unfamiliar to Earthly geologists.
Back here on earth, wave action, with the repeated reversal of flow, is great at sorting grains. There aren’t any gold deposits on beaches these days because wherever they’ve been found, they were mined out very quickly. But there are many beaches where black magnetite sand has been concentrated due to its higher density to quartz. If your beach does not have magnetite, look at the grain size: even quartz grains can often get sorted by size on wavy beaches. Apparently this idea came after scientists lost their fascination with latin, as this type of deposit is referred to simply as a “beach placer” rather than a “littoral placer”.
While we in North America might think of the Klondike or California gold rushes– both of which were sparked by placer deposits– the largest gold field in the world was actually in South Africa: the Witwatersrand Basin. Said basin is actually an ancient lake bed, Archean in origin– about three billion years old. For 260 million years or thereabouts, sediments accumulated in this lake, slowly filling it up. Those sediments were being washed out from nearby mountains that housed orogenic gold deposits. The lake bed has served to concentrate that ancient gold even further, and it’s produced a substantial fraction of the gold metal ever extracted– depending on the source, you’ll see numbers from as high as 50% to as low as 22%. Either way, that’s a lot of gold.
Witwatersrand is a bit of an anomaly; most placer deposits are much smaller than that. Indeed, that’s in part why you’ll find placer deposits only mined for truly valuable minerals like gold and gems, particularly diamonds. Sure, the process can concentrate magnetite, but it’s not usually worth the effort of stripping a beach for iron-rich sand.
The most common non-precious exception is uraninite, UO2, a uranium ore found in Archean-age placer deposits. As you might imagine, the high proportion of heavy uranium makes it a dense enough mineral to form placer deposits. I must specify Archean-age, however, because an oxygen atmosphere tends to further oxidize the uraninite into more water-soluble forms, and it gets washed to sea instead of forming deposits. On Earth, it seems there are no uraninite placers dated to after the Great Oxygenation; you wouldn’t have that problem on Mars, and the dry river beds of the red planet may well have pitchblende reserves enough for a Martian rendition of “Uranium Fever”.
While uranium is produced at Witwatersrand as a byproduct of the gold mines, uranium ore can be deposited exclusively of gold. You can see that with the alluvial deposits in Canada, around Elliot Lake in Ontario, which produced millions of pounds of the uranium without a single fleck of gold, thanks to a bend in a three-billion-year-old riverbed. From a dollar-value perspective, a gold mine might be worth more, but the uranium probably did more for civilization.
Speaking of useful for civilization, there’s another type of process acting on the surface to give us ores of less noble metals than gold. It is not mechanical, but chemical, and given that it requires hot, humid conditions with lots of water, it’s almost certainly restricted to Sol 3. As the subtitle gives it away, this process is called “lateritization” and is responsible for the only economical aluminum deposits out there, along with a significant amount of the world’s nickel reserves.
The process is fairly simple: in the hot tropics, ample rainfall will slowly leech any mobile ions out of clay soils. Ions like sodium and potassium are first to go, followed by calcium and magnesium but if the material is left on the surface long enough, and the climate stays hot and wet, chemical weathering will eventually strip away even the silica. The resulting “Laterite” rock (or clay) is rich in iron, aluminum, and sometimes nickel and/or copper. Nickel laterites are particularly prevalent in New Caledonia, where they form the basis of that island’s mining industry. Aluminum-rich laterites are called bauxite, and are the source of all Earth’s aluminum, found worldwide. More ancient laterites are likely to be found in solid form, compressed over time into sedimentary rock, but recent deposits may still have the consistency of dirt. For obvious reasons, those recent deposits tend to be preferred as cheaper to mine.
When we talk about a “warm and wet” period in Martian history, we’re talking about the existence of liquid water on the surface of the planet– we are notably not talking about tropical conditions. Mars was likely never the kind of place you’d see lateritization, so it’s highly unlikely we will ever find bauxite on the surface of Mars. Thus future Martians will have to make due without Aluminum pop cans. Of course, iron is available in abundance there and weighs about the same as the equivalent volume of aluminum does here on Earth, so they’ll probably do just fine without it.
Most nickel has historically come from sulfide melt deposits rather than lateralization, even on Earth, so the Martians should be able to make their steel stainless. Given the ambitions some have for a certain stainless-steel rocket, that’s perhaps comforting to hear.
It’s important to emphasize, as this series comes to a close, that I’m only providing a very surface-level understanding of these surface level processes– and, indeed, of all the ore formation processes we’ve discussed in these posts. Entire monographs could be, and indeed have been written about each one. That shouldn’t be surprising, considering the depths of knowledge modern science generates. You could do an entire doctorate studying just one aspect of one of the processes we’ve talked about in this series; people have in the past, and will continue to do so for the foreseeable future. So if you’ve found these articles interesting, and are sad to see the series end– don’t worry! There’s a lot left to learn; you just have to go after it yourself.
Plus, I’m not going anywhere. At some point there are going to be more rock-related words published on this site. If you haven’t seen it before, check out Hackaday’s long-running Mining and Refining series. It’s not focused on the ores– more on what we humans do with them–but if you’ve read this far, it’s likely to appeal to you as well.
2025-12-04 20:00:46
Now, Rock 5 ITX+ is no x86 board, sporting an ARM Rockship RK3588 on its ITX form-factor PCB, but reading this blog post’s headline might as well give you the impression. [Venn] from the [interfacinglinux.com] blog tells us about their journey bringing up UEFI on this board, thanks to the [EDK2-RK3588] project. Why? UEFI is genuinely nice for things like OS switching or system reconfiguration on the fly, and in many aspects, having a system management/configuration interface for your SBC sure beats the “flash microSD card and pray” traditional approach.
In theory, a UEFI binary runs like any other firmware. In theory. For [Venn], the journey wasn’t as smooth, which made it very well worth documenting. There’s maybe not a mountain, but at least a small hill of caveats: having to use a specific HDMI port to see the configuration output, somehow having to flash it onto SPI flash chip specifically (and managing to do that through Gnome file manager of all things), requiring a new enough kernel for GPU hardware acceleration… Yet, it works, it really does.
Worth it? From the looks of it, absolutely. One thing [Venn] points out is, the RK3588 is getting a lot of its features upstreamed, so it’s aiming to become a healthy chip for many a Linux goal. From the blog post comments, we’ve also learned that there’s a RPi UEFI port, even if for a specific CPU revision of the Model 5B, it’s still a nifty thing to know. Want to learn more about UEFI? You can start here or here, and if you want a fun hands-on example, you could very well start by running DOOM.
2025-12-04 17:00:00
Who’s interested in a brand new, from-scratch boundary representation (BREP) kernel? How about one that has no topological naming problem, a web-native parametric CAD front end to play with, and has CAD-type operations making friends with triangle meshes? If you’re intrigued, check out [mmiscool]’s BREP project.
Functioning (let alone feature-filled, or efficient) CAD systems are not a software project we see a whole lot of. Ones that represent models as genuine BREP structures but cleverly use mesh-based operations where it makes sense? Even less so.
In theory, CAD programs are simple: allow a user to define features, keep track of what they are and how they relate to one another, and perform operations on them as requested. In practice, it’s significant work. Chains of operations and dependencies easily become complex, volatile things and there is really no room for error.
Read [Arya Voronova]’s best practices for using FreeCAD to get a few hints as to what goes on behind the scenes in a modern CAD program, and the kinds of challenges the back end has to deal with, like the topological naming problem (TNP). A problem [mmiscool]’s implementation completely avoids, by the way.
There is a live demo at BREP.io which acts as a playground for the state of the project. You can get started by clicking the + button towards the top on the left panel to add features and operations to the history (like add a cube, then add chamfers or fillets, or extrude a face, and so on).
[mmiscool] points out that all computation is done client-side; even complex operations like fillets, lofts, and multi-body booleans execute directly in the browser with no need to be offloaded to a back end. BREP’s development is being documented on Hackaday.io and there is a video embedded below that gives an overview. Why don’t you give it a spin?
2025-12-04 14:00:58
Over on YouTube [Drake] from the [styropyro] channel investigates what happens when you take an enormous tungsten incandescent light bulb and pump 30,000 watts through it.
The answer: it burns bright enough to light up the forest at night, and hot enough to cook food and melt metal. And why on Earth would anybody do such a thing? Well [Drake] said it was because he wanted to outdo [Photonicinduction] who had already put 20,000 watts through a light bulb. Nothing like a little friendly competition to drive… progress?
[Drake] says he has purchased the most powerful incandescent light bulb ever made for commercial production. Rated for 24,000 watts (and operated at 30,000 watts) the enormous filament is made from tungsten. The starting current drawn by a light bulb is higher than the operating current, because the resistance of the filament increases with temperature, so it’s prudent to warm the device slowly. To this end [Drake] builds some custom wiring and dials to power the thing. Once that’s done, it’s off to the forest to play!
If you’re interested in over-the-top lighting shenanigans, you might enjoy reading about The World’s Longest Range LED Flashlight.
2025-12-04 11:00:32
Ever heard of MUMPS? Both programming language and database, it was developed in the 1960s for the Massachusetts General Hospital. The goal was to streamline the increasingly enormous timesink that information and records management had become, a problem that was certain to grow unless something was done. Far from being some historical footnote, MUMPS (Massachusetts General Hospital Utility Multi-Programming System) grew to be used by a wide variety of healthcare facilities and still runs today. If you’ve never heard of it, you’re in luck because [Asianometry] has a documentary video that’ll tell you everything.
MUMPS had rough beginnings but ultimately found widespread support and use that continues to this day. As a programming language, MUMPS (also known simply as “M”) has the unusual feature of very tight integration with the database end of things. That makes sense in light of the fact that it was created to streamline the gathering, processing, and updating of medical data in a busy, multi-user healthcare environment that churned along twenty-four hours per day.
It may show its age (the term “archaic” — among others — gets used when it’s brought up) but it is extremely good at what it does and has a proven track record in the health care industry. This, combined with the fact that efforts to move to newer electronic record systems always seem to find the job harder than expected, have helped keep it relevant. Have you ever used MUMPS? Let us know in the comments!
And hey, if vintage programming languages just aren’t unusual enough for you, we have some truly strange ones for you to check out.
