Today is another special day
2 a ago during #hedgewatch on #LaGomera's highest point during #sunset the "thing with the ring" happened
The #gemstone on the #EngagmentRing is a #sapphire a variety of the #mineral #corundum which is aluminium oxide #Al2O3
#Corundum var. #Ruby
#Afghanistan
Photo by Noor Ullah
By #GeologicalWondersToo / Karen Kemp
#GeologyPage #Nature #Minerals #Crystals #Gems #Nature #NatureLovers #NaturePhotography #Photographer #RockPorn
geology
Congratulations #wavellite! Your soft translucent green and your radial shapes have us seeing starbursts. Farewell to #corundum, the ancient mineral that condenses from solar nebulae, will be back.
Pink #corundum in a petrographic thin section (plane light), with green #clinopyroxene, field of view ~2 mm, Doğanşehir, Türkiye, #MinCup24
Corundum (as industrial sapphire) is not only scratch resistant, heat resistant, and acid proof; It can be a rod, tube, lens, or bearing. The only material that even comes close is diamond, but diamond is too brittle to make tubes.
You can even make tiny square vials called "cuvettes", which allow your sample to be heated to 1000s of degrees for spectral analysis.
(Most cuvettes are made of quartz, glass, or plastic, but for extreme tests, sapphire is sometimes used.)
I posted this last year, but here it is again:
This is a synthetic corundum rod from a hospital laboratory. These are called "industrial sapphire" despite the fact that they are pure Al2O3. Scratch resistant and non-reactive, a sapphire rod only a few cm long can be 2000C at one end and 20 C at the other, so you can test a wide temperature range with just one part.
Last week Clickspring posted a video showing how to use ruby (synthetic #corundum) bearings in precision instruments.
Corundum bearings are hard (mohs hardness 9) and shaped and polished to be low-friction.
#MinCup24 corundum vs wavellite
The tedious metal aluminium do make some fine minerals!
Wavellite is beautiful, but a bit of a one-trick pony, so its got to be #corundum for me. A signifier of wonderfully hot granulite or sanidinite facies metamorphism (or weird deep magmatic crystallization). A true rainbow mineral, taking on almost all colours of the spectrum, from red to violet, and doing them superbly well: ruby, sapphire, padparadscha..
Pic from here: https://www.gia.edu/gems-gemology/spring-2020-corundum-chromophores
#Corundum is famous by its other names, ruby and sapphire. This hexagonal crystal nearly tops the scale for hardness at Mohs 9, and may fluoresce under UV light. Crystals show off their shine when cut and polished, with some demonstrating asterism, 6- or 12-pointed stars of reflected or refracted light. Corundum was first synthetically grown in 1837.
Oh drat! I missed the start of #MinCup24
I'm glad #Rhodochrosite, #Corundum, and #Charoite are still in play.
#arsenuranospathite just because it's neat that so many minerals got together and made this! Even if y'know most of them are danger minerals... that's just more fun. Right?
(Like don't get me wrong, #corundum is neat too. I even own some. But 
.)
(Idk what my voting criteria is this year. 
) #MinCup24
via @MineralCup
We are half-way into #MinCup24 Round 2 match-up between #Arsenuranospathite and #Corundum. Corundum has the lead.
If you haven’t voted yet, now is your chance to influence which mineral advances. Vote below!
#MinCup24 Corundum vs arsenuranspathite: it's great that nature can bring enough fluorine, arsenic and uranium and aluminium together to grow crystals of arsenuranospathite, but it's got to be #Corundum for me! Here's Scotland's greatest gemstone: the 9.8ct "Saltire Sapphire" (the blue variety of corundum) from Loch Roag in Lewis, found and cut by Ian Combe, now in the collections of National Museums Scotland, in Edinburgh 
#Geology #Mineralogy #Corundum
#MinCup24 ROUND 1 MATCH 2: #Arsenuranospathite vs #Corundum
It's a tough choice, arsenuranospathite's elemental cocktail or corundum's sparkling gem qualities paired with high Mohs hardness? Campaign, learn, share, & VOTE!
Okay, okay, okay, folx. Stop everything you are doing and pay attention. It's September again, and with September comes the now well known #MineralCup! Today's bracket pitches the mighty and strong #corundum against this mouthful and beast of exotic elements that is #arsenuranospathite.
Gotta admit that I have a bit of a soft spot for the gemstones in that one, so corundum it is!
Vote here: https://www.mineralcup.org/2024/vote
Note: yeah I know I forgot yesterday...
