Specimen of turquoise fluorite carved into an eggs shape on a beige background. At the Natural History Museum in London.

For this holiday Mineral Monday, I present an itty bitty egg shaped from fluorite. #MineralMonday #GeoscienceBluesky ⚒️🧪

Long vertical quartz crystal with a transparent pyramidal top. The bottom is milkier with jagged edges. It sits on a metal mount on a frosted plinth in front of a grey background. At the Royal Ontario Museum.

Happy Geologists’ Day!!! Geology is for everyone, especially those who love cool rocks and minerals like this quartz!!! #GeoscienceBluesky #GeologistsDay

Deep purple blue nitrile gloved hand holds translucent slide of obsidian. It looked like dark Smokey glass with black flowy bands across with a small patch of red. It’s held above a white tray on a black background. At the Canadian Museum of Nature.

I just saw that it’s Geologists Day today!!! To share my excitement about geology, here is one of my favourite types of rock: obsidian!! This is a thin polished slice showing flow banding. #GeologistsDay #GeoscienceBluesky ⚒️🧪

The answer is the tourmaline group!! There are numerous mineral species in this group and a variety of colours! #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Three gems on a beige fabric in a diagonal. The top left is a yellow round brilliant cut on a small clear plinth. The label below says “round, brilliant-cut/locality unknown”. The middle is an olive green rectangular mixed cut with the label “rectangular, mixed-cut/locality unknown”. The bottom is a square cut deep green gem with a label “square, mixed-cut/Brazil”. At the London Natural History Museum.

Triple Guess the Gem time!! What mineral group do you think these three gems are? Hint: the cross sections of this group’s crystals would look triangular. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Specimen consisting of brown rock with veins of blueish purple opal on a black background. In front is a small transparent plexiglass label that says “Opale/Queensland/Australie” on it. At the Sorbonne.

So not quite a mineral for this week’s Mineral Monday, but this mineraloid opal is such a stunner. #MineralMonday #GeoscienceBluesky ⚒️🧪

Silvery and reddish mica specimen in the shape of a broken star with four points with multiple layers on a black background. At the Canadian Museum of Nature.

Specimen consisting of multiple thin books of pale yellow mica in the shape of stars coming off of matrix in multiple angles. It sits on a plastic wrap in a cardboard tray. At the Canadian Museum of Nature.

Have you ever seen mica in the shape of a star? Muscovite is more commonly seen as books of near hexagonal layers. #MineralMonday #GeoscienceBluesky ⚒️🧪

A small pale purple round specimen composed of many crystals mounted on a rod on a frosted plinth in front of a grey background. Sides of two specimens can be seen on either side. At the Royal Ontario Museum.

I love round specimens, especially snowball-like ones!! This is suolunite, a rare mineral. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer is calcite!! That double refraction means that when you look through a very clear calcite crystal things are doubled. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

A deep orange yellow rectangular gem mounted on a rod in front of a grey background. At the Muséum national d’Histoire naturelle.

Time for another Guess the Gem!! What mineral do you think this is? Hint: this mineral has double refraction. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

A large specimen of pink rubellite columnar crystals in radiating clusters along central points or lines, in fine grained lepidolite. It sits on the bottom shelf in a display case with a small label to the lower right. At the Natural History Museum in London.

Pink rubellite, usually a variety of elbaite (a tourmaline), in pale purple lepidolite (a mica) looking like a bunch of sea creatures. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer is zircon, a mineral used in geochronology!! #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

A round colourless brilliant cut gem reflecting lots of colours sits on a frosted plinth with the number 45 on it. It sits in front of a grey background. At the Royal Ontario Museum.

Another Guess the Gem!! What mineral do you think this gem is? Hint: this mineral is commonly used for the age dating of rocks. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Specimen of bright blue cavansite clusters that look like pom poms on a layer of small white crystals on a matrix. It sits on a frosted plinth with Cavansite written twice on it on a glass shelf in front of a grey background. At the Royal Ontario Museum.

Bright blue cavansite!! They look like bright pom poms! #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer to this Guess the Gem is the mineral quartz!! This mineral is very common and can make some beauties! #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Two clear gems, the one to the left is very large and oval on a small round white plinth, to the right is a rectangular gem. They sit on a glass shelf with a white 8 on it in front of a black background. At the Denver Museum of Nature and Science.

Guess the Gem time!! What mineral do you think these gems are? Hint: it’s very abundant on earth. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Specimen of polished agate in a thin tabular form showing grey wavy stripes similar to a strip of bacon ima white tray. At the Canadian Museum of Nature.

Grey bacon? Lace? This is agate, a variety of quartz, with beautiful layers. #MineralMonday #GeoscienceBluesky ⚒️🧪

Specimen on mounted on a green background below a title that says FOLDING. The specimen is brown and is a zig zag with the high hump on the left labeled ANTICLINE and the low bump to its right labeled SYNCLINE. The label below says: ANTICLINAL AND SYNCLINAL FOLDS IN QUARTZITE BOULDER CO., COLORADO At the Field Museum.

Love this old fold exhibit showing this gorgeous example of a anticline and a syncline. The oldest rock layers are on the bottom which helps identify the type of fold. These formed from pressure caused by compression. #FridayFold #GeoscienceBluesky ⚒️🧪

Specimen of labradorite that shows patches of bright blue, yellow green, and brown on the front surface. The sides are grey. It sits on a grey plinth on a grey background. A small frosted plastic label says Anorthite Anorthite on the lower left. At the Royal Ontario Museum.

Gorgeous technicolour labradorite!! This labradorescence shows a range of colours across the labradorite, a variety of feldspar that is primarily the mineral anorthite. #MineralMonday #GeoscienceBluesky ⚒️🧪

Pinecone made up of sulphur, so it’s a pale brown colour. It sits on a clear plexiglass plinth on a white background. At the Field Museum.

SO COOL!! Sulphur taking the shape of a pinecone!! It replaced the original material. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer to this Guess the Gem is watermelon tourmaline!! This tourmaline group variety has crystals with a pink centre and a green rim. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Two oval cabochons on a frosted plinth with the numbers 20 and 21 on it. The cabochons are both pale green on the bottom and pale pink on the top half. At the Royal Ontario Museum.

Guess the Gem!! What mineral, group, or variety do you think these gems are? Hint: this variety is named after food. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Close up of a side of a specimen consisting of clear to white quartz, pyrrhotite, and other minerals with deep green crystals of uvarovite speckled throughout. It sits on a black background. At the Hunterian.

Look at these gorgeous deep green crystals of uvarovite, some showing that classic garnet crystal shape!! It’s from Outokumpu, Finland. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer to this Guess the Gem is topaz!! This one is from Minais Gerais, Brazil, which is known for large crystals. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

A very large pale blue cut gem in the shape of a rounded rectangle on display on a white plinth on a white background. At the Natural History Museum in London.

Guess the Gem!! What mineral do you think this gem is? Hint: at 2,982 carats, it’s the largest cut gem in this museum’s collection! #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Gypsum specimen where there is a spray of small golden coloured columnar crystals with two larger ones growing out at a V shape. At the end of the V shape, forming a second layer of columnar crystals of a variety of sizes growing mostly above with larger crystals and below with smaller ones. It sits on a frosted plinth with the label “Gypsum/Gypse” on a glass shelf in front of a grey background. At the Royal Ontario Museum.

A beautiful sculptural golden gypsum specimen. Such a pretty mineral with many uses. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer is labradorite!! It is a feldspar variety in the albite-anorthite series that has the cool iridescent optical effect called labradorescence. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

An oval cabochon that sits on a small frosted plexiglass plinth on a grey background. The number 20 is on the plinth. At the Royal Ontario Museum.

Guess the Gem today!! What mineral or variety do you think this gem is? Hint: it has a schiller. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Big block specimen with its front face showing bright pink interspersed with some white crystals, with an outside brown weathered surfaces. It resembles a fatty steak. Some specimens sit in front of rose quartz, rhodonite, and fluorite. At the Great Northern Museum: Hancock.

So this one is bacon adjacent, it looks like wagyu beef 😂. This is the pink variety thulite of the mineral zoisite from Norway. #MineralMonday #GeoscienceBluesky ⚒️🧪

The answer is the mineral corundum, the red variety is ruby!! The blue variety is sapphire. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎