Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Tom86 on 29/09/2015 12:51:25

Title: What is this slate-like rock?
Post by: Tom86 on 29/09/2015 12:51:25

Hi everyone,

I've recently returned from a holiday in Mauritius where I found this piece of what I think is slate while walking along the beach on the south west coast.

It has a very shiny, almost a silvery metallic surface which I've not seen on a slate before, and I have not been able to find anything similar while searching on google.

I thought it was man-made at first, but you can see the same metallic colour on all the layers so I guess it must be natural. Someone has suggested that it could be Mica.

Photos:

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0072_zpstuc5uz3p.jpg&hash=07ab3c06e979868c38729ee0f5171eba)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0082_zps1vpy10v4.jpg&hash=e539d3553eb6eec0e67ed5a9830a1ba6)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0075_zpsqt9pglwf.jpg&hash=bd3c8962b09f871dc396915f30f74692)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0084_zpsav8frajg.jpg&hash=a8a8eb651f99a2b6d25379687779803a)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0083_zpsprji5nsk.jpg&hash=dddeb92f584dc6551aa8201fd01b1ff3)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi209.photobucket.com%2Falbums%2Fbb116%2FT0M4ever%2FIMG_0077_zps6kzxacrq.jpg&hash=0d55fa0f7eb6fc123ddcecee41f29678)

Hopefully the photos are ok, it is quite difficult to capture the metallic look of it.

Title: Re: ID for this slate like rock
Post by: Bill S on 02/10/2015 22:14:43

Just from the pics, I would say its a Mica Schist.

The silvery flakes are almost certainly Muscovite Mica.  The darker flecks may be Biotite Mica.  If the colours are true, there is greenish mineral that could be chlorite.

Title: Re: ID for this slate like rock
Post by: Bass on 03/10/2015 02:28:19

BillS has it right. somewhere between phyllite and schist (the difference being that the mica flakes are larger in schist).