Abbreviation
|
Texture/structure
|
Definition
|
---|---|---|
Phenocryst percent: | ||
a | Aphyric | <1% |
sp | Sparsely phyric | 1%-2% |
mp | Moderately phyric | 2%-10% |
hp | Highly phyric | >10% |
Groundmass crystallinity: | ||
c | Holocrystalline | 90%-100% crystals |
hc | Hypocrystalline | 50%-90% crystals |
hyh | Hypohyaline | 10%-50% crystals |
G | Hyaline | 0%-10% crystals |
Grain size: | ||
pc | Phanerocrystalline | Phaneritic |
cg | Coarse grained | >5 mm |
mg | Medium grained | 2-5 mm |
fg | Fine grained | 1-2 mm |
ap | Aphanitic | <1 mm |
mc | Microcrystalline | <0.5 mm (= aphanitic) |
cc | Cryptocrystalline | Not visible under binocular microscope (= aphanitic) |
Vesicularity: | ||
nov | Nonvesicular | <1% |
spv | Sparsely vesicular | 1%-5% |
mov | Moderately vesicular | 5%-20% |
hiv | Highly vesicular | >20% |
Alteration log: | ||
v | Veins | |
f | Unaltered | <2% |
s | Slight | 2%-10% |
m | Moderate | 10%-40% |
h | High | 60%-80% |
vh | Very high | 80%-95% |
co | Complete | 95%-100% |
Mineral form: | ||
e | Equant | |
t | Tabular | |
b | Bladelike or lathlike | |
Vesicle type and vesiculation structure: | ||
ve | Vesicles | |
vd | Diktytaxitic texture | |
pv | Pipe vesicles | Hollow |
sv | Segregation vesicles | |
vc | Vesicle cylinder | Filled with vesicular segregation material |
hvs | Horizontal vesicle sheets | Segregation veins; filled with vesicular segregation material |
mv | Megavesicles | Domed roof and flat floors, may have segregation material at their base |
vz | Vesicular zone | >10 vol% macroscopic vesicles |