Distinctive features:  
Texture and granularity, composition, occurence.

Colour: 
Dark grey, dark greenish-grey to black, depending on the percentage of dark minerals present.

Texture and granularity: 
Granular, though not particularly coase. Hornblende crystals may give it the appearance of a porphyritic texture.

Composition: 
There is more hornblende than feldspar and more plagioclase than orthoclase. The presence of quartz is uncommon. but if it is present the rock is then granodiorite (quartz diorite) rather than diorite.

Field associations: 
Associated with both granite and gabbro intrusions, into which they may subtly merge.

Varieties:
Granodiorite, when minor amounts of quartz are preesent.

 

Worldwide, but particularly in the eroded roots of fold mountains.

 

Ornamental -- capable of taking a high polish.