Mika McKinnon Profile picture
Sep 4, 2018 17 tweets 8 min read Twitter logo Read on Twitter
Oh no. It’s the most contentious time of the year for geo-folk. I usually stay out of it, but some of these minerals are going to make me stan hard.

Lineup below. Hashtag to Follow or Mute is #MinCup2018
Olivine is the defending champion. Here’s why it’s badass from my Ode to Olivibe last #MinCup:
But diamonds... Diamonds are a more unlikely champion.

Ignore the social/economic burden of diamonds, because it’s not the poor lil minerals’ fault that humans have been terrible over the sparkly.

Instead, let’s talk mineral properties.
Diamonds are dead simple: They’re Carbon.

As a geophysicist forced to memorize chemical composition by sadistic petrologists, I appreciate being able to scrawl “C” for full credit.

Plus, it’ll never be confused with it’s allotrope, graphite. Easy ID is my friend.
Q: How do you ID diamond when it hasn’t been cut & polished into a sparkly wonderland?
A: Rub it against something. Does the mineral scrape your thing? How about that other thing? And that one? If it scrapes EVERYTHING, thar be diamond because it’s literally the hardest material.
Q: But I don’t wanna scrape shit!
A: Fine. Toss it in fire. Or a pool of lava. Liquid lead? Whatev, you ain’t melting it because diamonds are tough fuckers with the highest melting point of any mineral at 4090°C
Q: Diamonds are tough, got it. But why?
A: Diamonds have an EXTREMELY dense crystalline structure (densest atom packing of any mineral). This means toughness, but it also means ridic heat conduction.

Have a diamond nearby? Touch it.

It’s cooler than the surroundings. Science!
Q: Pfft, forget practicality, I’m here for the sparkle-rainbows!
A: Diamonds are transparent over the greatest number of wavelengths (they’re clear), but also have excellent fire, with luster from greasy to adamantine depending on cut.

Total internal reflection
Every diamond is an optics lesson. The cut determines how light bounces around — angle, depth & number of faces influences how much sparkle you’ll get.

You cannot cut a gorgeous diamond without understanding optics. Every diamond ring is #SciArt. Schematic is light refracting & reflecting in diamonds that are cut too shallow, too deep, or just right
But wait! Just in case you’re STILL not sure you have a diamond, you can flash a UV light at it because diamonds fluoresce!

Diamonds typically fluoresce light blue, but sometimes white, yellow, orange, or red.
How diamonds form can be beyond trippy.

Imagine an asteroid. It has graphite in it. Now slam it into the Earth in a violent cataclysm of doom.

That’s how you get Lonsdaleite, a diamond polymorph with graphite crystal structure (& a rare mineral named for a woman).
But normal diamonds come from kimberlite pipes.

Kimberlite pipes are a volcanic structure we can find now, but they don’t happen anymore. Because...?! Stop asking, just get digging for diamonds!
What we know:
Diamonds form in the mantle.

Kimberlite pipes violently brought diamonds to the surface by covering 100+ miles within hours, or they would’ve degraded into graphite.

Uh... gas, maybe? Except where did the gas come from??
My vote for Round 1 of #MinCup2018:
Fuck Olivine, it won last year.

Diamonds are the hardest, most heat resistant, densest, & clearest mineral, plus they have neat heat conductivity, fluorescence, & luster. The badass origin story is just bonus.

Aside: I wear a ring of reclaimed heritage diamonds with different cuts, thus different sparkles.

A sunbeam hit it on my flight earlier & I was captivated making the light dance.

Diamonds: For when your inner cat takes over. Or when your inner unicorn needs to restock rainbows.
Q: I can only imagine a cut, sparkly diamond. What does a rough diamond look like?

A: Colour depend on trace inclusions or plastic deformation of crystal structure. Usually clear, but can be white, black, brown, grey, yellow, orange, or rarely blue, green, red, pink, or lilac.

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More from @mikamckinnon

Oct 2, 2018
A woman won the Nobel Prize in Physics?!?!?!? AHHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!

Right. Time to learn about Donna Strickland, the 3rd woman to EVER be awarded the prize. cbc.ca/news/technolog…
I still think the Nobel Prizes (particularly for physics) are sexist garbage with this whole “50 years between each woman” trend they’ve got going on, but I’ll take learning a new name, dammit.

& she’s not even a variant of Maria!!!
I’m not covering the Nobel Prizes, but if any of my women scicomm peeps are doing explainers on chirped pulse amplification of lasers, please ping so I can boost your work. 💥
Read 21 tweets
Sep 14, 2018
I made a plea for compassion for people who didn’t evacuate. It included the dreaded p-word.

My inbox has been ...interesting.
Camp 1: “THANK YOU! Me/my people can’t evac because xyz. Of course I don’t want to die or endanger rescuers; I did the best I can!”

Their stories are making me so fiercely proud of how determined they are to survive in the face of overwhelming odds against them.
Camp 2: “I live in a country where society has higher standards for providing basic healthcare. What do you mean America doesn’t ensure everyone can evacuate?! Surely not!”

Yeah, I KNOW. It’s unreal.
Read 7 tweets
Sep 13, 2018
For very specific technical reasons:
- It takes until well after a disaster to establish the official death count as we prioritize saving lives.

- Official death counts are conservative: actual recovered bodies with cause of death linked to the disaster.
Recovering bodies is not always feasible, especially as disasters have a nasty habit of killing response personal.

In BC, the Hope landslide is a grave for 4 people whose bodies were never recovered from under the 47 million cubic meters of rock.
Estimated death counts are extremely tricky. You need to think extremely critically about every assumption made.

Often an actual number is less important than a qualitative description: Every family was devastated. Infrastructure was destroyed for months. Daily life ended.
Read 7 tweets
Sep 10, 2018
Dear south coast: If you’re under mandatory evacuation orders, pack up and LEAVE.

Listen to your local officials. Please?

Info for SC in advance of Hurricane Florence:
Even if you think it’s excessive, or over-cautious, or you’ve survived worse. I promise emergency managers don’t issue orders for their own entertainment.

Evac orders are a damn hard call between logistics, vulnerability of destabilization, & loss of trust if it’s conservative.
Read 19 tweets
Aug 30, 2018
@markmccaughrean 1. The text of the resolution changed since Monday. Neither the conference website nor the eNewspaper has the updated text.
@markmccaughrean 2. The two head dudes presented their argument to rename, allowed a few comments with no rhyme or reason, ate time refuting criticism, & only named speakers who supported them, before cutting off comment without warning to give a closing statement of support.
@markmccaughrean 3. The Nay vote was presented as “rejection to approve,” because that’s not at all confusing.
Read 9 tweets
Aug 18, 2018
The number of Last Jedi haters in my mentions telling me I’m wrong is kinda delightful.

Like, I did this EXACT sequence of actions last time I was in Utah when to figure out if I was in sand or salt. Hating the movie (fools) doesn’t make the geo less plausible.

Q: How does a terrestrial condiment end up on an alien planet?
A: Salt is halite, a naturally occurring mineral of sodium & chloride. It’s not even unique to Earth inside our own solar system (see: a million news articles on Mars rock salt)

More: earther.gizmodo.com/the-amazing-ea…
Q: Pfft, soldiers don’t need to know geology!
A: Not all rocks are stable. Weight & explosions on wrong geo produces sinkholes, outgassing, & more.

Specifically, when lasers hit that white crap, is it a silica mineral (quartz) that will melt into glass? Lick test for y/n
Read 4 tweets

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