Jump to content

Recommended Posts


Hi Brad… your photos are a bit blurred, but your sample appears to be a “schist”. Schist is a generic term for a foliated metamorphic rock. It displays well-developed foliation (leaves or sheaves of leaves), often through inclusion of mica. It represents the ultimate stage of metamorphism. 

A schist is usually derived from fine-grained sedimentary rock such as shale that has been exposed to some combination of heat / pressure. Individual minerals in schist have grown during metamorphism so that they are easily visible to the naked eye. 

Foliation takes place when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied. Schists are named for their mineral constituents, for example, mica schist is notably rich in mica such as biotite or muscovite. From what I can see, that is what is depicted in your photo. Below I’ve included a close-up depiction of a mica schist so that you can compare your sample to it as a confirmation. Hope this helps.

Jim.

114611779_MICASCHISTSF14YG.JPG.19825a1f7daedc9856025dbbc7b6d0d5.JPG

  • Like 8
Link to post
Share on other sites

Hi,

I am around 75% certain that Jim Hemmingway  has  correctly  identified your specimen. As he said the photo is fairly blurry so that other 25% lurking in my mind says that this could also be a specimen of one of the Iron/Copper Sulfides like chalcopyrite or bornite. If tiny pieces of the specimen are easily removed by your fingernail and look like tiny thin sheets then it is definitely a phyllite or decomposing muscovite mica schist. If the specimen is harder and more compact with chunky pieces breaking off then my 25% minority guess is probably closer to the correct ID in which case we are looking at a mineral or combination of minerals.

  • Like 1
Link to post
Share on other sites

Oh I quite agree Jeff. Brad’s photos could depict a number of common sulfides / arsenides and there are other possibilities. For example, I have a few ore samples exhibiting native silver ‘horns’ and veinlets protruding from oxidized surface niccolite embedded in a light brown carbonate rock, that look very similar to Brad’s sample. But I seriously doubt this is what Brad has found in his area, as these are quite rare.

We make our best guess based on the info provided and what we think we see in the photo. The one photo appears to depict some foliation, but there’s no way to be certain. This is why I included a schist photo for him to do a comparison. It ensures that he’ll know if his sample is schist or something else. 

Jim.
 

  • Like 2
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Similar Content

    • By mshin89
      Hi!
      This rock was recently discovered in the garden after deep digging. It has a blackened outer surface which appears to resemble a fusion crust, and is mostly stone with iron streaks throughout and rusting present. It weighs 38 lbs/17.2 kg, and is roughly 27cm long and 15 cm wide. The rock is rounded on one side and has a straight(ish) edge on the other where it likely broke off from a larger rock (I have dug further and can't find anything else). The rock is lightly attracted to a reasonably strong magnet but the attraction is not strong enough for it to stick to the rock independently. I have attached pictures here. Any help identifying it would be appreciated, though I appreciate it's unlikely to be a meteorite as these are very rare findings!
      To summarise:
      Is a magnet attracted to it? Yes (light attraction)
      Is it heavier than other rocks ? Yes
      Does it have a dark, thin crust on the outside? Yes
      Does it have a lighter color on the inside? Yes



    • By CVISChris
      Found these today up stream from my normal digs.  Look like game pieces too me.  
      They are stamped on both sides.   


    • By Rick N. MI
      I was hoping it was piece of a meteorite but it isn't. 
      I was using the Equinox 800 and this piece hit hard. It is very light. It's not magnetic. The ID is 1. Could it be a piece of coal?
       



    • By Kris0072000
      can anyone help me in identification?

    • By Purplehays69
      I found this years ago while sniping a creek. Went to throw it out of the crack but it was very heavy for its size. Sticks very hard to my pick magnet.

    • By Allen M
      I was out in a area that I was in last week and came across this today. There was a vein running between the Quartz’s. Here are some pictures of what I found. 
       
      Anybody have any thoughts on this. 







×
×
  • Create New...