Also, the #MinCup23 #zircon victory has been published if you’d like an appetizer while you ready your strategies for #MinCup24! Mineral Cup is coming September 1st!!

https://www.mineralcup.org/about/2023

Oh no, #perovskite is far behind #rhodochrodite Guys, the look is not everything.

In Germany, there is a saying "Quadratisch, praktisch, gut.", which is admittedly from a commercial for chocolate, but it describes perovskite very well. It's square (OK, cubic or pseudocubic), practical (many applications) and just good (interesting genesis).

Go for the inner values. Vote for chocolate (much better than bacon)! Vote #perovskite #MinCup23.

#MinCup23

Both #dioptase (Cu6(Si6O28*6H2O) and #vivianite (Fe3(PO4)*8H2O) contain crystal water, but vivianite has more. Vivianite is much softer (Mohs 1,5-2) than dioptase (Mohs 5), and at least Cu keeps its valence when exposed to air.

Vote stable and green! Vote #dioptase!

There are all these glorious colors and facettes . Vote #quartz #MinCup23

#Quartz as tiger eye modification shows chatoyancy, an effect that resembles cat's eyes. #MinCup23

So it's #quartz against #stibnite today in this second round of #MinCup23. For me, my decision is crystal clear: #Quartz for the win. These are stbnite and some quartz single crystal exhibits from the mineral collection at University of Münster.

Went for my Sunday morning run and the road was blocked by 20 m of ankle-deep mud from a blocked drainage channel. My running shoes are soiled. No way, I will not vote for that today (although the paw prints are adorable). Vote #zircon! #MinCup23

Match 11 of #MinCup23 today and this will be a tough one: shiny mineraloid #opal against good, old bubbling #calcite. Opal has the looks but I prefer a crystal structure... See some fabulous examples of #calcite to convince you...

#Calcite can form very well-defined crystals but sometimes also looks a bit plain and beige. All samples from mineral exhibition at Uni Münster.

OMG, I just voted and it's s a tie #MinCup23 #Adamite

#Vivianite I had to look up last year. It is a blue-green hydrated iron phosphate (Fe2(+II)[PO4]2 x 8H2O) with monoclinic crystal structure and acicular or fibrous aggregates.

But look at this : #Vivianite pseudomorph after shell from Kerch, Crimean Peninsula, Ukraine (size: 5.6 × 4.6 × 2.7 cm). #MinCup23

Rob Lavinsky, iRocks.com

Some crystal clear #topaz from the mineral collection at Uni Münster. #MinCup23

I will vote for #crocoite this time, because I can combine two of my favorite hobbies: minerals and cooking - I love paella and a good paella needs saffron. #MinCup23

Unfortunately, #crocoite is on the #DoNotLick list...

Charles Haynes

Already match number 5 in this year's #MinCup23: it's #dioptase vs. #crocoite - dark green copper silicate against vibrant red lead chromate.

#Dioptase is called copper emerald (Kupfersmaragd) in Germany, while #crocoite refers to the resemblance to saffron from the crocus plant.

Crocoite: JJ Harrison
Dioptase: Rob Lavinsky, iRocks.com

Today its dreamy blue #sodalite against the antimony ore #stibnite in #MinCup23 I am still undecided...

#MinCup23 Asparagus has a special place in the heart of us Germans, so I was happy to learn that there is a greenish variety of #fluoroapatite that is called Spargelstein (asparagus stone). Also it shows luminescence under UV light. Very pretty, but...#Zircon is a colorful gemstone which is host matrix for e.g. rare earth elements and uranium and thorium, which makes zircons extremely useful for geochronology. And it can be produced synthetically e.g. for jewellery.
Apatite: Didier Descouens

Behold #quartz. Still some hours left to vote #MinCup23

#MinCup23 Let's talk about supporting #quartz, the reason why the Mineral Cup was invented in the first place...It must remain in the game!

#Quartz can have a multitude of colors ranging from crystal clear to dark brown. It is one of the most common minerals on Earth. Many varieties like rose #quartz or tiger eye are used as gemstones.

The first commercial LEDs were based on synthetic #Moissanite. 3H-SiC was used for yellow LEDs in and 6H-SiC was found to emit blue light. Unfortunately, SiC has an indirect bandgap, therefore nowadays, the more favorable GaN is used, which has a direct band gap and is about 100 times brighter. #MinCup23

#MinCup23 Moissanite's chemical formula is SiC. Synthesis of SiC was achieved in 1891 by Edward Goodrich Acheson. It is a really hard material (9.5 Mohs), so it is used as an abrasive or for durable components like car brakes.But SiC is used in electronics, too, because it is a wide band gap semiconductor. There are several polytypes of SiC: 2H, 3H, 4H and 6H and the band gap strongly depends on the configuration (3.02 eV for 6H, 3.27 eV for 4H, 3.17 eV for 2H).

I'll start some early campaigning for #Moissanite, because synthetic #Moissanite (SiC) is also super-interesting from a materials science perspective #MinCup23

Natural #Moissanite has a huge color variation from green and blue to black depending on composition. It was first identified in 1904 by Henri Moissan in a sample from the Canyon Diablo meteorite found near Barringer Crater.
A Silver - BYU Mineral Specimens 799 USGS Photographic Library