Text only
Physical Geology Helpful Lab Hints
Igneous Rock Texture Flow
Chart
(texture terms are in red)
Are most of the mineral crystals
visible to the naked eye?
- Yes: Are all of
the crystals the same size?
- Yes: Are the crystals greater than 1 inch?
- Yes: Pegmatitic
- No: Phaneritic
- No: Phaneritic
& Porphyritic
- No: Is
the rock full of holes?
- Yes: Does
the rock have a glossy shine to it when turned in the light and does it
feel like sandpaper?
- Yes: Glassy
& Vesicular
- No:
Aphanitic &
Vesicular
- No: Is
the sample glassy?
- Yes:
Glassy
- No:
Is the sample made of fragments of rock and
ash?
- Yes:
Pyroclastic
- No:
Are all of the crystals the same size?
- Yes: Aphanitic
- No: Aphanitic
& Porphyritic
Back to igneous rock ID
page.
copyright © 2002 Mike Phillips (includes all
photos)
last updated: 06/01/06