PlanetGeo: The Geology Podcast

Chris's college mineralogy lab final was 20 specimens, and one of them was a quartz crystal his professor had dipped in graphite. The luster was off, the color was off, and Chris got it wrong even though every other property said quartz. That one exam question shows why mineral ID is hard and why you need a system. This episode lays out that system.
We finish the minerals chapter of the Camp Geo audio textbook with polymorphs, which are minerals with the same chemical composition but different crystal structures. The classic example is graphite and diamond. Both are pure carbon, but in diamond each carbon atom bonds to four others instead of three. That denser arrangement is stable at high pressure, which makes polymorphs useful clues to where a rock formed. Along the way we get into synthetic diamonds, companies that turn ashes into gems (Jesse will pass on that one), and a white dwarf star that Chris describes as a 2,500-mile-wide diamond, nicknamed "Lucy" after the Beatles song.
Then Chris walks through the mineral ID flowchart he's refined over decades of teaching. Start with luster, because metallic or non-metallic decides your next step. Metallic minerals go straight to streak, and non-metallic minerals go to hardness. Chris brackets hardness on the Mohs scale with things you already carry: a fingernail (2.5), a copper penny (3.5), a knife or glass plate (5.5), and feldspar (6) and quartz (7) if you can find them. From there it's cleavage vs. fracture (the key test for telling feldspar from quartz) and why chemical bonding controls both. Then streak, where shiny silver specular hematite from Michigan's Upper Peninsula leaves a reddish-brown powder. Last come specific gravity, color, crystal form, and a few specialty properties like magnetism and fluorescence.
Color gets a public trial, because amethyst, rose quartz, and milky quartz are all the same mineral. That leads to a rescue story: Chris hauled a rose quartz specimen down a scree slope and everyone else thought it was junk. He still has it and says he was right. Then the quiz, which Chris aces.
In this episode
The graphite-dipped quartz that cost Chris a question on his mineralogy final
Polymorphs: same composition, different crystal structure
Graphite vs. diamond, and why four bonds beat three at high pressure
Synthetic diamonds, memorial diamonds, and a diamond-core white dwarf
Why mineral ID needs a structured workflow
Luster first: metallic vs. non-metallic decides your next test
The Mohs hardness scale and the fingernail–penny–knife–glass bracket
What controls hardness: the weakest link in the chemical-bond chain
Cleavage vs. fracture, and how to tell feldspar from quartz in the field
Streak: silver hematite, reddish-brown powder
Specific gravity, the "heft test," and how density separates zircons in the lab
Why color is the least reliable property (amethyst, rose, and milky quartz)
Crystal form: diagnostic when crystals have room to grow, which is rare
Magnetism, fluorescence, and willemite under a black light
The quiz: Chris goes 2 for 2
Up next: sedimentary rocks
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You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

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There are roughly 7,000 known minerals on Earth. You need to know about ten of them. In the third installment of the Camp Geo Intro to Minerals series, Chris and Jesse finish the minerals chapter by working through the rock-forming minerals — the short list that makes up the overwhelming majority of the rocks in Earth's crust — and by explaining where minerals actually come from in the first place.
Before the top-ten list, they step outside the silicates. Just as the silica tetrahedron defines the silicate family, other mineral groups are defined by their own dominant anion: the carbonates (CO₃²⁻, home to calcite, arguably the second most important mineral group on the planet), the sulfates (gypsum, which Jesse grew up seeing mined in Michigan), and the phosphates (apatite — the stuff your teeth are made of, and a mineral Jesse's lab dates routinely). Along the way, Jesse clarifies a point from Part 1: an anion can be a single charged atom or a charged molecule like CO₃ or SiO₄.
Then, the four environments in which minerals grow — igneous (crystallizing from cooling magma or lava), metamorphic (solid-state recrystallization under heat and pressure), hydrothermal (precipitating from hot circulating water, as at Yellowstone and, far more commonly, at mid-ocean ridges), and sedimentary (salts left behind as cool saline water evaporates, think Bonneville Salt Flats). Chris flags the one that trips students up most: hydrothermal and sedimentary both precipitate minerals from water, but only one of them involves heat. This detour also produces the episode's best story: the day the two of them drove up a sketchy dirt road to the Gore Mountain garnet quarry in upstate New York without permission, watched a black Chrysler 300 come roaring up behind them, and left with about two tons of volleyball-sized garnets in the back of Chris's F-250.
Finally, the countdown: feldspar, quartz, the micas, the olivines, the pyroxenes, the amphiboles (hornblende, for intro purposes), the clay minerals, calcite, dolomite, and halite plus gypsum. Seven of the ten are silicates, and Chris and Jesse tie each one back to its tetrahedral structure from Part 2 — framework, sheet, single chain, double chain, single tetrahedron. They cover the tricks for telling calcite from dolomite (a drop of HCl fizzes like Alka-Seltzer on one and like flat pop on the other), why mica rarely survives in sedimentary rocks, why clay minerals are basically what feldspar turns into when it hits a stream, and Chris's field-tested (and decidedly not medically endorsed) use of crushed limestone as heartburn relief.
The episode closes with Jesse's quiz question for Chris, which Chris promptly declares "has potential" but needs reworking.
Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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Ask an intro geology class what the most abundant element in the crust is and, year after year, the answer comes back "carbon." It doesn't make the top eight. That gap between what feels right and what the planet is actually made of is where this lesson lives.
Chapter 2 of the Camp Geo audio textbook starts with the layered Earth — crust, mantle, and core — and why Chris's peanut M&M (with a caramel injection for the liquid outer core) beats Jesse's apple. Then the chemistry of each layer: an iron core, a silicon-oxygen-magnesium mantle, and a crust that's wrapped around the planet like tissue paper on a bowling ball and dominated by silicon, oxygen, and aluminum.
Because silicon and oxygen run the show, one building block runs the mineral world: the silica tetrahedron, a pyramid with silicon in the middle and four oxygens at the corners. Chris and Jesse walk through the five ways those pyramids link up — single tetrahedron, single chain, double chain, sheet, and framework — with bead curtains, books of mica from a Black Hills collecting trip, and quartz as the fully-connected end member. Jesse gets rambly about charge balance; Chris reins him in. Chris goes two for two on the quiz and critiques the question-writing anyway.
In this episode
Crust, mantle, core — chemical layers, and why the peanut M&M wins
What each layer is made of, and how thin the crust really is
The most abundant crustal elements (spoiler: not carbon)
The silica tetrahedron and why the 3:1 oxygen-to-silicon ratio forces sharing
The five silicate structures, simplest to most connected
Micas, pegmatite "books," and the muscovite on Chris's bookshelf
Why quartz is SiO2 and needs nothing else
The quiz: Chris goes 2 for 2
Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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Instagram: @planetgeocast
Twitter: @planetgeocast
Facebook: @planetgeocast
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Email: planetgeocast@gmail.com
Website: https://planetgeocast.com/

Ask a room full of intro geology students whether a snowflake is a mineral and almost every hand says no. Ask why, and someone will tell you it's because no two snowflakes are alike. Chris Bolhuis has been asking that question for 25 years — he asked it of a young Jesse Reimink sitting in his high school classroom — and the answer is the whole point of this lesson.
It's been a while since we've released an episode on the Planet Geo feed, and there's more coming (plus a few projects we can't wait to announce). In the meantime, we're sharing the intro chapter of our Camp Geo audio textbook — the first lesson of the Physical Geology course you'd take in your first semester as a geology major. Several podcast platforms now display chapter artwork, which is close to how the Camp Geo mobile app works, so this is also a bit of an experiment: tell us how it lands.
Chris and Jesse start where geology starts: the five criteria something has to meet to be a mineral. It has to be solid, naturally occurring, inorganic, have a definite chemical composition, and have a definite crystalline structure. The first three are easy (though "inorganic" is on shaky ground as mineralogists warm to biominerals — this rule may not survive the decade). The last two are where students get hung up, so they slow down: quartz is always SiO2, halite is always NaCl, and swap potassium in for sodium and you've got a different mineral entirely.
Then a quick tour of the chemistry you half-remember from high school. Chris blows an atom up to the size of a 30-seat classroom — the nucleus is the tip of a pencil dangling from the ceiling, and everything else in the room is electron cloud. Jesse walks through protons, neutrons, and electrons, and why the loosely held electrons are what drive bonding. Ionic bonds transfer electrons (sodium hands one to chlorine, and a cation and anion snap together); covalent bonds share them. Chris's "paw-sitive" mnemonic and Jesse's parenting advice about covalent bonding are both, by mutual agreement, terrible. They both work.
The episode closes with the analogy that ties it all together: a five-gallon bucket of tennis balls dumped on the floor. There's one best way to stack them. Add a bucket of marbles and the best way to stack changes — a different composition forces a different structure. Because there is a definite chemical composition, there is a definite crystalline structure. Elements make minerals, minerals make rocks, rocks make the planet.
And then Jesse quizzes Chris. Chris goes one for two and files a formal complaint about question number two.
In this episode
Why we're releasing Camp Geo content on the Planet Geo feed (and what's coming)
The five criteria for a mineral — solid, naturally occurring, inorganic, definite chemical composition, definite crystalline structure
Why "inorganic" may get dropped from the definition as biominerals gain acceptance
Quartz vs. halite vs. the potassium version — what "definite composition" really means
Is a snowflake a mineral? Working through all five criteria (yes, and you're a snowflake too)
The classroom-sized atom and the pencil-tip nucleus
Protons, neutrons, electrons — and why electrons do all the bonding work
Ionic bonding: sodium, chlorine, cations, anions, and "paw-sitive"
Covalent bonding: sharing electrons instead of stealing them
The tennis-ball-and-marble analogy for crystal structure
Definite composition → definite structure → minerals → rocks
The quiz: Chris goes 1 for 2 and disputes the scoring
About the series
Camp Geo is Chris and Jesse's audio textbook version of an introductory Physical Geology course, built for the Camp Geo mobile app, where each lesson comes with a stack of images to follow along with. This is Chapter 1. Chris Bolhuis is a nationally recognized earth science teacher in Michigan; Dr. Jesse Reimink is his former student and now a professor in the Department of Geosciences at Penn State.
Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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What happens when a finance guy who's never heard of lithium takes a job in a small North Carolina town because it's near where his favorite author lived?Joe Lowry is the founder of Global Lithium LLC, host of the Global Lithium Podcast (239 episodes and counting), and author of the new memoir Lithium Confidential: Confessions of a Corporate Misfit. He spent 35 years in the industry — including years in Japan and China — and for a stretch in the 1990s he personally controlled essentially all of the lithium supply going into the world's first commercial lithium-ion batteries.This is a longer, less traditional episode for us, and it's worth every minute. Joe walks through the entire lithium cycle from rock to cathode, explains why the industry started as a hydrogen bomb program, and gives an unusually blunt read on where the industry is headed — including his line that there's no Smackover lithium without direct lithium extraction, and why he thinks the first real success there lands around 2029.There's also plenty here for students and early-career geologists: Joe's argument that you should learn the industry, not just deploy your geology skills, and his advice on what actually makes a career durable.Some things we get into:Why lithium was in Post-it Notes, blue jeans, and grease long before batteries
The full flow sheet: spodumene → calcine → lithium sulfate → carbonate → hydroxide, and why the "midstream" means cathode, not chemicals
Hard rock vs. Atacama brine vs. sedimentary (Thacker Pass) vs. Smackover oilfield brine
Why grade matters: 600 ppm Smackover vs. sub-100 ppm produced water (sorry, Marcellus)
How the market went from 300,000 tonnes LCE in 2020 to nearly 2 million today
The 2022 spike to $80,000/t and what happened after
Why Joe called BS on the high-nickel/hydroxide narrative and was right about LFP
Sodium-ion: real use cases, or a CATL press release every time lithium ticks up?
What "crappy brine" means, and the fraud problem in African spodumene
Commodity or specialty chemical? Why fungibility is the whole argument
Getting fired as the best thing that ever happened to him
Timestamps
00:00 – Intro
01:30 – Welcome, and the strange experience of being recognized by voice
03:10 – How Joe got into lithium: oil, corporate raiders, a gold mine, and a small town near Asheville
06:00 – Lithium before batteries: glass, grease, and the dye in Post-it Notes
08:30 – Japan, China, and being the only person who thought batteries would matter
12:30 – What the "midstream" actually is, and why battery plants without cathode plants don't solve anything
13:30 – The hydrogen bomb origin story: DOE, Lithium Corp of America, Foote Mineral
14:20 – Hard rock processing, start to finish
15:45 – Enter brine: Silver Peak, then the Atacama
17:20 – Sodium sulfate, the glass industry, and putting the blue in blue jeans
18:50 – SQM arrives and the price goes from $2/lb to 68 cents
21:20 – Greenbushes: a tantalum mine that happened to have lithium
23:00 – China's assets, lepidolite, and how CATL became a third of the market
25:20 – 300,000 tonnes to 2 million: "what's grown that fast that's not software?"
26:40 – Thacker Pass: wrong flow sheet, right rock, and a $2.3B DOE loan
29:40 – "Soft rock," the McDermitt caldera, and Tom Benson
30:20 – The Smackover, bromine wells, and why you can't build ponds in Arkansas
31:30 – DLE: what counts, what's actually working, and what's still a declared victory
33:15 – What makes a brine "crappy"
33:40 – Grades, produced water, and why Pennsylvania shouldn't get too excited
34:20 – Arkansas is all-in; Exxon is slow-walking it
37:50 – Garbage spodumene, African supply, and lithium that showed up in China with no lithium in it
38:50 – The four-minute mile: why 2029 is the year to watch
40:40 – Recycling and the circular economy reality check
42:50 – Is it still the lithium decade?
43:20 – China controls processing — and depends on everyone else for supply
44:40 – LFP vs. NMC/NCA, and the call Joe got right
46:30 – What's actually in your iPhone
48:00 – Sodium-ion: niches, not a replacement
50:00 – BESS, aging grids, and a prediction Joe made in 2010
51:55 – Advice for students and young geologists entering lithium
53:40 – On AI, and bulletproofing what you do
54:00 – Starting the Global Lithium Podcast: Tim Ferriss, a LinkedIn post, and a studio in Buenos Aires
55:20 – Downloaded in every country on Earth except Bhutan
57:10 – The Korean listeners who finally explained themselves
1:00:10 – The real value of a podcast is what's said before and after the record button
1:02:30 – Australia 34%, US 30%, and why resource economies listen
1:05:10 – Which lithium conference should a student actually go to?
1:09:00 – Writing Lithium Confidential: five life goals from January 1, 1982, and a granddaughter
1:11:30 – Why the book has exactly 100 chapters
1:16:20 – Commodity or specialty chemical? The fungibility argument
1:18:20 – Specs, secret sauce, and selling the same product twice
1:20:00 – The freedom that comes with getting fired
1:20:25 – Joe's best day in the lithium business
1:23:30 – Best deposits he's ever visited: Pilgangoora's vision, Liontown's build
Links
Lithium Confidential: Confessions of a Corporate Misfit — available in print and Kindle
globallithium.net
The Global Lithium Podcast — wherever you get podcasts
Joe on LinkedIn: Joe Lowry | On X/Twitter: @GlobalLithium (note the handle — not the Australian company)
CampGeo mobile app — pegmatites, mineral basics, and all our back catalog
planetgeocast.com | @planetgeocast
Download the CampGeo app now at this link.

On the app you can get tons of free content, exclusive images, and access to our Geology of National Parks series.
You can also learn the basics of geology at the college level in our FREE CampGeo content series - get learning now!

Like, Subscribe, and leave us a Rating!

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Instagram: @planetgeocast
Twitter: @planetgeocast
Facebook: @planetgeocast
Support us: https://planetgeocast.com/support-us
Email: planetgeocast@gmail.com
Website: https://planetgeocast.com/