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This page will contain information on submitting samples to the NMGRL for 40Ar/39Ar dating.
If you are currently interested in dating
rocks/minerals at the NMGRL,
please feel free to contact us at (505) 835-5271
In the meantime, here are a few rocks and minerals we have dated at the NMGRL.
Rocks and Minerals Available for 40Ar/39Ar Dating
| Volcanic | Plutonic | Metamorphic | Hydrothermal | Sedimentary |
|
Rock/Mineral
|
Percent K2O
|
Advantages
|
Disadvantages
|
|
Anorthoclase |
<3%
|
High potassium; Homogenous
|
Rare excess argon observed (melt inclusions) |
|
Biotite/Phlogopite
|
~3%
|
Often easy to separate |
Hydrous; May contain excess argon
|
|
Glass
|
variable
|
Common; Homogeneous; Easy to prepare
|
Alters easily; Susceptible to 39Ar recoil
|
|
Groundmass/Wholerock |
variable
|
Very common; Easy to prepare/analyze |
Inhomogeneous; May contain inherited argon
(excess argon or xenocrysts); Often altered
|
|
Hornblende
|
<1%
|
Common
|
Low potassium; Hydrous; May contain excess
argon
|
|
Plagioclase
|
<2%
|
Very common
|
Low potassium
|
|
Pyroxene
|
<1%
|
Common
|
Low potassium; Hydrous; May contain excess
argon
|
|
Sanidine
|
>3%
|
High potassium; Very homogenous; Easy to
separate/analyze
|
.
|
|
Biotite/Muscovite
|
3-7%
|
High potassium; Common; Often easy to separate
|
Hydrous; May contain excess argon
|
|
Hornblende
|
<1%
|
Common; Often easy to separate
|
Low potassium; Hydrous; May contain excess
argon
|
|
Potassium Feldspar
|
>5%
|
High potassium; Common; Easy to separate
|
Rare excess argon observed (fluid inclusions)
|
|
Biotite/Muscovite
|
3-7%
|
High potassium; Common; Often easy to separate
|
Hydrous; May contain excess argon
|
|
Hornblende
|
<1%
|
Common; Often easy to separate
|
Low potassium; Hydrous; May contain excess
argon
|
|
Alunite
|
.
|
Capable of dating low temperature
mineral deposition |
Hydrous; susceptible to 39ArK recoil and
reactor induced 40Ar loss
|
|
Jarosite
|
.
|
Capable of dating low temperature
mineral deposition |
Hydrous; susceptible to 39ArK recoil and
reactor induced 40Ar loss
|
|
.
|
.
|
.
|
.
|
|
.
|
.
|
.
|
.
|
|
Glauconite
|
~3-5%
|
Capable of dating sedimentary deposition
|
Susceptible to 39ArK recoil and reactor
induced 40Ar loss
|
