Crustal rocks: 2-3 ppm Sea water: cca. 3,3 ppb
You can also say that they are radioactive.
Silicate minerals such as quartz and feldspar are the most common minerals located in earths crust
Uranium is a metal, solid and radioactive at room temperature.
silicates
SILICATES, they make up 90% of the crust.
Carbon
gold
Zinc.
Quartz and feldspars are the most common silicate minerals of the crust.
17 only
Carbon
Mercury.