Rock of the Week #5

Ah, finally a "structure rock".
Here are the questions:
1. What is this rock?
2. What is missing from the little cubic holes?
3. Why does the rock have that rectangular-prism shape?

Hint for the online audience: the words "Merced Falls" are written on the rock, this wouldn't give anything away to the south african students but I had to tell you anyway.

Solution to Rock of the Week #4:

Thanks to Johann Diener for the interesting rock!

1. (1 pt) 2 minerals?
: 1 point given for either feldspar or pyroxene.

2. (1 pt) Rock type?
: Komatiite.

3. (1 pt) Locality:
: any komatiite locality acceptable, e.g. Barberton Belt.


MJC Rocks said...

Well, believe it or not, I live a 45 minute drive from Merced Falls, and it provides the first stop on my class field trips to Yosemite...so I am going to shut up and let a few people guess at this one. It is a neat rock for the weekly quiz, though!

sandyshoes said...

...is it pyrite missing from the cubic holes?

Ron Schott said...

Is this a form of "pencil" cleavage? Also, I concur on the pyrite diagnosis for the holes, though I wonder about a lack of iron staining.