Your favourite rock (geology, not sweets)

[farmerbarleymow]

Hello

I was talking to someone about rocks, and wondered - what is everyone's favourite rock?

Not sweet rock like http://www.urban75.net/forums/threads/best-rock.273473/

Rocks are great, and make good pets and house decorations. Don't need walking, and the only downside is that they gather dust. But you can talk to them.

So suggest you favourite rock, with pictures if you like. [should this be in the science bit?]

Mine is, apart from my lumps of nice gneiss, Shap granite or lumps of the Great Whin Sill. But I love all sorts of rocks, including an ironstone one I found on a beach. It smells really metallic which is lovely.

Excuse the pun, but geology rocks!

Hmmm - should I add a poll?

 

[moose]

I have a little piece of pure black obsidian that I picked up in a river bed in Idaho when I was a mere slip of a girl, and a lump of green basalt from Birchover in Derbyshire that holds down the papers on my desk at work. Also a lump of black lava from a beach Reykjavik.

 

[Belushi]

Anthracite, the beautiful king of coal.

 

[DotCommunist]

0.1g per £10

 

[Dillinger4]

I like obsidian as well. And jade.

 

[pogofish]

Gabro makes for some great mountains:

Mind you, Old Red Sandstone has to run a pretty close second!

 

[gentlegreen]

I suppose granite - though that's more like a collection of minerals.

Can we stray outside of geology / petrology ?
I used to collect minerals - not necessarily rare or exotic ones.
There were always iron nodules in the flowerbeds at school.

So simple iron oxide - from the ochre that was held as mystical by cave painters.



I have full-height limonite -coloured curtains in my back room - and speakers to match :-



To curvy crystalline forms - like Goethite :-

 

[Tankus]

Is that Skye in the top one (Cullins?)

Mines quartz veined greenschist ....epic when polished ......always fancied a kitchen worktop in it

 

[farmerbarleymow]

I have a little piece of pure black obsidian that I picked up in a river bed in Idaho when I was a mere slip of a girl, and a lump of green basalt from Birchover in Derbyshire that holds down the papers on my desk at work. Also a lump of black lava from a beach Reykjavik.

Hi moose! Does the obsidian have perlitic cracks aka devitrifrication stresses? That shows its age.

 

[weltweit]

I prefer sedimentary over igneous rocks, I think fossils may prefer sedimentary deposits which would be a good thing. But I know nothing about rocks

 

[farmerbarleymow]

Some beautiful pictures - thanks everyone.

Mineraltastic/mountainastic!

 

[Kameron]

Lamprophyres are my favorites to hold in your hand. This is normally intrusive, found in dikes, and often very pretty.

My favorite unit is the Torridonian sandstone supergroup.

And schists are very nice. But all the Coarse feldspathic sandstone and pretty schists don't top the Lamprophyres.

 

[pogofish]

Is that Skye in the top one (Cullins?)

Top one is Connemara. The other two are Cullins.

 

[farmerbarleymow]

I prefer sedimentary over igneous rocks

Heresy! Igneous rocks!

 

[farmerbarleymow]

To curvy crystalline forms - like Goethite :-

View attachment 33497

A beautiful haematite.

 

[farmerbarleymow]

Anthracite, the beautiful king of coal.

Agree. A lovely example of almost pure carbon - hello 300 million years+ ago!. Nice and shiny.

 

[farmerbarleymow]

Is that Skye in the top one (Cullins?)

Mines quartz veined greenschist ....epic when polished ......always fancied a kitchen worktop in it

That is truly gorgeous. I'd love anything of that polished in that - it's beautiful.

 

[cesare]

Rock crystal - does that count?

 

[Miss-Shelf]

I really like the type of granite found in the channel islands

I also like chalk because it feels nice and reminds me of beaches

I have a little rock collection by my front door from beaches
I have some from Isles of scilly (must be granite) jersey and some beaches in wester ross. got some chalk from cuckmere haven, and bits and pieces from sussex and dorset beaches - who knows what they are - I just like the look of them
Will post pics when I'm back home

really I like shells too and just want to hijack your thread with beach talk sorry

 

[farmerbarleymow]

http://www.earth.ox.ac.uk/~oesis/nws/nws-a98-9.html#handspec

This is a type example of my oldest rock - a Lewisian gneiss, from around 1.75 billion to 2.9 billion years ago (-ish). From the Laxfordian Orogeny.

I felt older than this when I woke up this morning sadly...

 

[farmerbarleymow]

Gabro makes for some great mountains:

That is gorgeous. Where is it?

 

[farmerbarleymow]

0.1g per £10

Not 'distilled' if you please! Only truly natural materials allowed here.

 

[farmerbarleymow]

Rock crystal - does that count?

Everything natural counts.

 

[Miss-Shelf]

http://www.earth.ox.ac.uk/~oesis/nws/nws-a98-9.html#handspec

This is a type example of my oldest rock - a Lewisian gneiss, from around 1.75 billion to 2.9 billion years ago (-ish). From the Laxfordian Orogeny.

I felt older than this when I woke up this morning sadly...

I had never heard of gneiss until I read this book
http://www.amazon.co.uk/Old-Ways-Jo...8&qid=1370813644&sr=1-1&keywords=the+old+ways
and he talks of an artist who makes things with it

 

[Miss-Shelf]

That is gorgeous. Where is it?

is it gruniard bay?

 

[cesare]

Everything natural counts.

I like all sorts of rocks, but there's something about quartz that I like a lot. And watching a documentary earlier that had a few minutes describing Islamic rock crystal carving was brilliant

 

[farmerbarleymow]

Here are some pictures of my favourite rocks.

Shap granite:

and the MIGHTY High Force:

Edit [found some better pictures of High Force in full spate]

The truly mighty Great Whin Sill. An igneous intrusion covering approximately 1,500 square miles of the North East of England.

These pictures are, in my view, the best place in Upper Teesdale. High Force - a truly superb place, and one I've spent many a happy hour at.

This is one of the places where the sill outcrops. The rock is so intensely hard that the River Tees has a hell of a job in eroding it. The result is that it thunders over the outcrop, and the roar of the waterfall is astonishing.

There's nowt better than dipping your feet in the freezing water on a summer day. It truly is a beautiful sight, in a lovely wooded valley - one of England's best waterfalls and one largely forgotten.

And more peaceful...

 

[farmerbarleymow]

For the geeks out there, the reason why Shap granite is so angular is that the pink crystals are orthoclase feldspar. The cleavage angle of OF is about 87°and thus almost 90°, hence 'orthodox' in angular terms.

At the moment I can't recall the cleavage angle of plagioclase feldspar (the white feldspar also common in granitic rocks), but will check...and get back to you if it is at all interesting.

Which it probably isn't!

 

[weltweit]

Before I rode my motorbike from Land's End to John O'Groats I learnt of a practice of taking a lump of rock from the bottom and throwing it in the sea at the top to redress the balance so to speak. I don't know what the rock was or how much it increased my fuel consumption on the journey but I took it and then in the end I threw it - as required!!

 

[farmerbarleymow]

Before I rode my motorbike from Land's End to John O'Groats I learnt of a practice of taking a lump of rock from the bottom and throwing it in the sea at the top to redress the balance so to speak. I don't know what the rock was or how much it increased my fuel consumption on the journey but I took it and then in the end I threw it - as required!!

Pissing in the wind I think. The south is doomed to sink beneath the waves, and the north will survive due to isostatic rebound.