Tag Archives: snowflake

Snowflake Obsidian – Day 25 of the Mineral Advent Calendar

Posted on by

0

This holiday season, why not get a mineral every day instead of chocolate? Today’s mineral is Snowflake Obsidian find out more about it below..

Well that’s it for the Mineral Advent Calendar this year, I hope you enjoyed it! I finish us off today with the only snow we are likely to see in the UK today and that is Snowflake Obsidian.

Not this snowflake, that's one I made!!! Because I really wish it would snow.

Not this snowflake, that’s one I made!!! Because I really wish it would snow.

Snowflake Obsidian forms as a variety of Obsidian, which has inclusions of the mineral Cristobalite in the Obsidian. The Cristobalite forms these gorgeous white snowflake shaped growths that give rise to the name. So in a way the final mineral today is two-for-the-price-of-one! BUT Obsidian is not actually a mineral – it is a type of volcanic glass that has crystals of silica so small you can’t see them with the naked eye. We call it crypto-crystalline.

Snowflake Obsidian from Wikipedia.

Snowflake Obsidian from Wikipedia.

Obsidian:
Chemical formula: SiO2
Colour: Black to grey black
System: N/A
Hardness (Mohs): N/A
Can you find it in the UK? No

Christobalite:
Chemical formula: SiO2
Colour: Colorless, white, also blue grey, brown, grey, yellow
System: Tetragonal
Hardness (Mohs): 6 – 7
Can you find it in the UK? Yes

Whatever you are celebrating this winter season, I wish you joy!!

Whatever you are celebrating this winter season, I wish you joy!!

 

For more information about Snowflake Obsidian please visit the MinDat website.

 

Ice – Day 7 of the Mineral Advent Calendar

Posted on by

1

This holiday season, why not get a mineral every day instead of chocolate? Today’s mineral is Ice find out more about it below..

So at this point you might be looking at the screen and going – ‘ICE?! That’s not a mineral!’ But in fact it is – it’s just a mineral with a really low melting point, so it’s one of the few minerals that you can not only see commonly in its natural form, you can also synthesise it too! Yes, you can create your own mineral synthesising environment by filling a tray with water and putting it in your freezer. And although this is still ‘ice as a mineral’, because you force the mineral to grow in an unnatural environment, it rarely forms the kind of structures you would associate with natural ice crystals. And as it is #MicroscopyMonday, what better way to look at ice than through a microscope.

There are two types of ice that I relate to the season; the first is natural, falls from the sky and I very rarely get to see in the UK. Yes I am talking about snow, and if you have never seen a snowflake through a microscope you are in for a treat, because they are exceptionally beautiful.

Absolutey gorgeous photos of the stellar dendrites form of ice, please visit Kenneth Libbrecht's webpage form more spectacular imagery.

Absolutey gorgeous photos of the stellar dendrites form of ice, please visit Kenneth Libbrecht’s webpage form more spectacular imagery.

The second type of ice we see commonly at this time of year comes out of tub in your freezer (my favourite is chocolate – obviously!) and this photo is one taken by Steve Furzeland for some research being done at the Electron Microscopy Centre in Plymouth – yes, it’s ICE CREAM!

A great image of an ice crsytal in Ice Cream, taken by the Plymouth University Electron Microscopy Centre.

A great image of an ice crsytal in Ice Cream, taken by the Plymouth University Electron Microscopy Centre.

 Ice:

Chemical formula: H2O
Colour: Colourless to white
System: Hexagonal
Hardness (Mohs): 1½
Can you find it in the UK? Er, yes? Seriously, you even have to ask!!

Ice. It gets everywhere! (image from prettymyparty.com)

Ice. It gets everywhere! (image from decoration idea supplied on prettymyparty.com)

There are many forms of ice beyond the branching six-sided (because they are hexagonal – get it?) shapes so as I say go back and look at Kenneth Libbrecht’s website for more forms.

For more information about Ice please visit the MinDat website.

Check out more Plymouth University Electron Microscopy images here.