Rebel authorities in the Democratic Republic of the Congo say more than 200 people have been killed in a mine collapse that occurred in Rubaya in the country's east on Wednesday.
Reuters news agency reported the death toll, citing authorities from the rebel group M23, which controls the site.
The mine produces coltan, a metallic ore that contains the critical material tantalum, which is used to produce electronic components for smartphones and other products.
The Associated Press says over 15 percent of the world's supply of tantalum comes from mines in Rubaya.
There were concerns about possible collapses, as tunnels are dug manually and safety measures are insufficient.
The United Nations points out that the mines have become a source of funding for M23's offensive in the east of the country.
The rebel group, backed by neighboring Rwanda, has repeatedly clashed with DRC government forces.
Prompted by a strong interest in critical minerals, the administration of US President Donald Trump has stepped in to mediate peace.

Quiz 1:
What material is mined in Rubaya, according to the article?
A. Gold
B. Coltan
C. Diamonds
D. Copper

Quiz 2:
According to the article, what percentage of the world’s tantalum supply originates from Rubaya?
A. Approximately 5%
B. Around 10%
C. Over 15%
D. Roughly 20%

Quiz 3:
Which country is reported to be backing the M23 rebel group?
A. Rwanda
B. Uganda
C. Tanzania
D. Zambia

[Answer block]
Answers:
Quiz 1: B
Quiz 2: C
Quiz 3: A