I've never visited St Nectaire, in the Auvergne, Fance, but it needs to be on my list. One of the fastest depositing petrifying places on Earth I think. They've also been using this wonderful natural process to make strange artworks since the C18th. 😊 🤓
The brilliant contemporary American-Scottish artist Ilana Halperin worked with them and made some amazing pieces...
https://www.auvergnevolcansancy.com/en/site-culturel/fontaines-petrifiantes-de-saint-nectaire/
Rock-forming minerals
Common minerals combine to make rocks
The Earth's crust is made of over 2,000 minerals. Of these, the most abundant are feldspar, quartz, #calcite, dolomite, mica, pyroxene, #amphibole, garnet and olivine. Because they combine to make rocks, these are called 'rock-forming minerals.
Feldspars are the most abundant minerals in the Earth's crust.
Rock-forming minerals
Common minerals combine to make rocks
The Earth's crust is made of over 2,000 minerals. Of these, the most abundant are feldspar, quartz, #calcite, dolomite, mica, pyroxene, #amphibole, garnet and olivine. Because they combine to make rocks, these are called 'rock-forming minerals.
Feldspars are the most abundant minerals in the Earth's crust.
#Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines
Sometimes, Open Source developers just make me laugh and facepalm at the same time. I was looking at the docs for Apache Calcite adapters and for some reason there is an adapter which lets you query your data in *PIG LATIN*?!?! #OpenSource #Calcite #ApacheCalcite #FOSS
Huanglong (Yellow Dragon), #China! 🐉 This #nationalpark is known for its #colorful travertine pools (saw so many walking down the #mountain!) formed by #calcite deposits, as well as diverse #forest ecosystems, snow-capped peaks, waterfalls, and hot springs, and was also declared a World Heritage Site by #UNESCO.
At an altitude of 3,552-3,576 m (my face has been tingling—had no idea that was a symptom of altitude sickness ‘til now), this is the Multi-Colored #Pool,
#Greenland's #caves preserve an ancient #climate archive https://phys.org/news/2025-10-greenland-caves-ancient-climate-archive.html
"Gina Moseley and her team traveled to one of the most remote regions on Earth—Greenland's far northern coast. The Cove Cave can only be reached by small aircraft and hiking. During the expedition, the researchers discovered #calcite deposits that can form only when the ground is unfrozen and water is flowing. They show that northern Greenland was once free of #permafrost and much wetter than it is today."
17-Oct-2025
Drip by drip: The hidden blueprint for #stalagmite growth
stalagmites grow into flat-topped pedestals, classical columns, or pointed cones not by chance, but according to a single controlling factor – the Damköhler number – which represents a balance between the rates of #calcite precipitation and the flow of water
Gli eterei e zannuti guardiani dei branchi, che nascono grigi, poi diventano bianchi
https://www.jacoporanieri.com/blog/?p=43165
#animali #parchi #africa #namibia #elefanti #mammiferi #polvere #minerali #paesaggio #circostanze #strano #visioni #notte #sole #comportamento #creature #natura #biologia #ecologia #calcite #argilla #terra #sostrato #branchi
Gorgeous #Calcite with #Fluorite and #Quartz From Yaogangxian Mine, Hunan Province, #China..(HWD): 7 X 5 X 3.5 cm
Photo Copyright ©️ Fabian Wildfang
By #GeologyWonders
#Geology #GeologyPage #Nature #Minerals #Crystals #Gems #Nature #NatureLovers #NaturePhotography #Photographer #RockPorn
#Fluorite with #Calcite from Cave-in-Rock, Hardin County, llinois, #USA.
S:55x87х66тт
Photo Copyright ©️ peanuts_minerals
By #GeologyWonders
#Geology #GeologyPage #Nature #Minerals #Crystals #Gems #Nature #NatureLovers #NaturePhotography #Photographer #RockPorn
Look at this #calcite crystal and its super strong birefringence, yielding two distinct optical paths! And yes, that's Captain Haddock, a subtle reference to the strong polarization effects in calcite sunstones, likely used as navigational aid by seafarers in the Viking Age. #MinCup25 #teamcalcite
Vote here (only a few hours left!):
Calcite vs Perovskite (planetary science edition)
Most carbonates on Mars are Fe and Mg-rich (so siderite-dolomite) but the infamous meteorite Allan Hills 84001 also containts some rare calcite.
(Mg, Fe)SiO3 perovskite (same structure as CaTiO3) can form by dissociation of olivine in shocked martian meteorites (for example: shergottite Dar al Gani 735) recording extreme pressure and temperature conditions of at least 25 GPa, 700°C.
Calcite and perovskite may be battling it out in #minCup25 today, but they can be friends too. Here's an image of a layered rock with perovskite (dark brown) and clear blebs of calcitic carbonatite melt, and spiky crescumulate calcite crystals. This strange rock is from one of the Benfontein kimberlite sills in South Africa. Image is about 15mm wide. Sample is in the #Hunterian museum collections in Glasgow. #ThinSectionThursday #Geology #perovskite #Calcite #mineralogy
#MinCup25 More reasons to vote for the incredible #calcite and its stunning crystallographic diversity. In Viktor Goldschmidt's monumental "Atlas der Krystallformen" calcite alone gets 153 plates showing different forms and habits. Enjoy them all here, although it may take a while! 🤩 😂 🤓
https://archive.org/details/atlasderkrystalltaf02gold/page/3/mode/1up
#MinCup25 More reasons to vote for the wonderful #calcite. Does any mineral, or any crystalline phase, show as much diversity of habit as calcite? In Matthew Forster Heddle's epic "Mineralogy of Scotland" he illustrates 29 whole-page plates of calcite habits just from Scotland. Enjoy scrolling through them here:
https://archive.org/details/mineralogyofscot01heddrich/mineralogyofscot01heddrich/page/n251/mode/2up
#MinCup25 Two fine minerals facing off in today's bout: the exotic, chemically and structurally intriguing perovskite vs the ubiquitous chameleon that is calcite.
https://mastodon.scot/deck/@MineralCup@mastodon.social/115143274766404499
This year I'm going for #calcite Among other things, it makes for some completely bonkers, unusably fragile gemstones. like this one, which turns a ray of light entering the stone into 8 rays leaving the stone. More here: https://www.gia.edu/gems-gemology/winter-1984-calcite-hurlbut (with free link to full pdf)
#MinCup25 Round 1 Match 4: This match of heavy hitters is bound to end in heartbreak as classic #calcite faces off against futuristic #perovskite.
We love them both, but only one can continue on to Round 2!
Vote: https://www.mineralcup.org/2025/vote/r1m04
Results: https://www.mineralcup.org/2025/results/r1m04
Fantastic #Proustite on #Calcite From Bouismas mine, Bou Azzer District, Zagora Province, Drâa-Tafilalet Region, #Morocco.
Photo ©️ Fine mineral photography
By #GeologyWonders
#Geology #GeologyPage #Nature #Minerals #Crystals #Gems #Nature #NatureLovers #NaturePhotography #Photographer #RockPorn
