A big discovery
When the discovery was announced last year, independent resource assessors estimated that the underground gas deposits in Tanzania contained around 54 billion cubic feet (1.5 billion cubic meters) of helium, mixed with mainly nitrogen gas. But, a reanalysis of the helium concentrations in the gas deposits indicate they may hold more than 98.6 billion cubic feet (2.8 billion cubic meters) of helium gas.
More than originally thought
Helium forms very slowly on Earth inside ancient rocks, caused by the radioactive decay of heavier elements like uranium. The scientist think that volcanic heat can liberate the helium from the rocks where it forms and trap the gas in underground pockets.
In volcanic areas like Tanzania's Rift Valley, the trapped helium can seep through weaknesses in the crust and bubble up through hot springs, like the one in this photo.
Solution to a problem
A resource prospecting company called Helium One hopes to start supplying helium gas from the Tanzanian field by the end of 2020.
Taking cues from history
For the most recent tests in late 2016, the researchers used a portable mass spectrometer to make measurements of the helium concentrations from the gas seeps in real time.
Helium gas is inert and non-toxic, and only a small processing plant will be needed to start production of Tanzanian helium for the international market.