Basalt or Gabbro?

[ngangey]

Based on visual inspection how can I classify the bedrock on a riverbed if it is Gabbro or Basalt?

 

[cvg]

color and grain size?

 

[fattdad]

Gabbro is coarser grained - almost like granite. Basalt is uniformly dark gray or black and fine grained. Here's a chart on igneous rocks:

f-d

¡papá gordo ain’t no madre flaca!

 

[cvg]

basalt gray or black
gabro more green

 

[ngangey]

fattdad your the best..Thank you for the information..

 

[BigH]

fattdad - where did you access the chart?

 

[fattdad]

Here's the web page that hosts the image.

http://geology.csupomona.edu/alert/igneous/igclass.htm

f-d

¡papá gordo ain’t no madre flaca!