Purple Laker - Lake Superior - Rock Identification

[Smithsh6]

I recently went to Michigan and went agate hunting. I found this nice purple laker. This was my first rock hunting expedition so I am not familiar with rocks or minerals. Could someone tell me what this rock is made of or called. Does it have any value? It weighs 10.5 ounces. Also should I cut it open?

 

[Eu_citzen]

Chip an edge and show us the fresh exposure. Could be quartz or chalcedony.

 

[stdenis_jd]

LSA's can often be so darkened by iron inclusion that it's hard to see the agate striations - usually a wet pic makes it harder to identify but in this case get it wet and take another close up pic if you can get a clear exposure. Often LSA's like this will benefit greatly from soaking in warm mineral oil to prolong the "wet" look.

As far as value, one that size is probably worth quite a few bucks if it is in fact a LSA. If it is, I would personally cut it because like Brazilian Agate it makes the lines more clear in a slab than in the full rock.

If there isn't any translucency and banding (lines/striations), it is quartzite and only worthy of being a garden stone unfortunately