#Igneous Rock

[hiyutekivigil]

two pretty views on gabbro thin section in crossed polarised light

[luci-luck]

Papa Pie was less than pleased once he found out what Sandstone (Pinkie) does for a living.

[nouveaucrystals]

Reblog if you love Rainbow Obsidian 🌈 Which would you choose? Shop here

[misu4sh]

My friend who's in another city showed me these lovely local minerals. Some calcite, chalcopyrite, selenite, gypsum, dolomite, and anhydrite. (⁠ ⁠◜⁠‿⁠◝⁠ ⁠)⁠♡

This was also very interesting. Any thoughts or knowledges to share? Would appreciate it (from a first year geology student ;))

[aleydraw]

THE PIE FAMILY

[alexdti]

A moment of pure happiness for our little Pinkie Pie

How we met - Pinkie Pie - Page 14

New page each Monday

[mineralsrocksandfossiltalks]

Monday Musings

Let's talk about macrocrystalline quartz vs microcrystalline quartz. I see sooooo many people argue over these in rockhounding groups that I think it is important to address. First, they are the same chemical formula

Whether it's amethyst or chert this is what it is on an atomic level. So, what makes them different?

Well, a big part is how they are formed. Macrocrystalline quartz grows by adding molecules to the surface, layer by layer. It essentially grows in three different environments:

1.) In silica-rich molten rock during cooling and solidification

2.) in pegmatites, during and following pneumatolytic processes

3.) In hot water solutions of silica under various conditions (usually hydrothermal) The water is between 100 and 450 degrees Celsius and often at high pressures. (underground)

There are no free SiO2 molecules in the solution, instead quartz crystals grow by the addition of dissolved orthosilicic acid (H2SiO4). The four photos above show the process on a very basic level.

In igneous rocks, the formation of quartz is caused by positively and negatively charged ions floating around in the molten rock soup. In fact, these silicate ions cause magmas to become more viscous. SiO4- usually forms long chains in the magma.

When magmas cool rapidly, like at the point of eruption, the chains don't have time to break and new bonds to form so silica-rich magmas often for volcanic glass or pumice.

When magmas cool slowly under the surface, like in granite, crystals of different minerals will in the melt in order of chemical composition. With granite, micas form first, the feldspars, then finally quartz. Because quartz is last, it usually doesn't have great shape since it is filling in all available space.

Quartz in magmas will often have an onion-like internal structure of layers added on top of each other reflecting a gradual change in the residual liquid parts of the solidifying magma.

Okay, now for the microcrystalline quartz: chert and chalcedony (and the bazillion names given to different colored varieties of that).

Chert can form under two different processes: biochemical and and replacement through solution in water.

Biochemical chert is formed when siliceous skeletons of marine plankton are dissolved during diagenesis with silica precipitating out from the resulting solution.

Replacement chert forms when other material is replaced by silica usually by water such as petrified wood.

Chert has the same properties as macrocrystalline quartz i.e. same hardness, fracture, etc.

Chalcedony also forms by precipitation of dissolved silica in water but it is usually formed from watery silica gels which give it the botryoidal look it is well-known for.

It is often deposited in cavities and fractures, spaces too small to form proper quartz crystals, by the release of silica from weathering of other rocks (often volcanic in origin).

Isn't quartz wild?

[cakearcade]

[ask-sentient-vehicles]

Who do the narrow gauge engines think is best pony?

:)

(I kinda hate scrolling through MLP on the internet cuz the fandom's horrible -_-)

so many tags wth

[reddar88]

one big happy family

[hiyutekivigil]

another week another friday looking at rocks

[zjfgz]

First video. feel free to ask topics related to geology, hydrology, biology and environmental Toxicology

[nouveaucrystals]

Reblog if you love Rainbow Obsidian 🌈 Which would you choose? Shop here

[misu4sh]

To my geology gang out there who has any idea how to start studying for petrology, can anyone maybe send sum helpful tips, pdfs, materials that are free online, videos, and all that stuff.

This is for a petty thing I'm about to do to prove shit to people. Thank y'all in advance (⁠*⁠＾⁠3⁠＾⁠)⁠/⁠～⁠♡

[ancientfrozenglaciershark]

Not enough photos of the Palisades Sill on here!

Those 2 are my pics but they do not nearly represent how awesome she is. evidence:

I love you earth, I love you time, I love you millions of years of erosion exposing giant sheets of intrusive igneous rock for me to gawk at

[alexdti]

It's party time!

How we met - Pinkie Pie - Page 24

New page each Monday