Assertion: neptunium | /r/HasProperty | man-made
Facets:
Source sentences:
text: Most neptunium is man-made.
text: It used to be very rare and for a long time, people thought that neptunium didn’t exist in nature and was a man-made element, but we now know that very small amounts can be found in the Earth’s crust.
text: Neptunium (Np) is a man-made actinide metal, grayish in color, which lies on the periodic table of elements between uranium and plutonium.
text: The only neptunium (Np) available on Earth is man-made.