Sierra Leone

Total and Min/max: Published estimates and official figures coincide, indicating at least 300,000 ASM miners. Supposedly, these numbers refer mainly to gold and diamond mining and do not include ASM on the “some coltan and zircon” or development minerals. To compensate, it appears reasonable to estimate a range of 300-400,000 with an average at 350,000.
Female participation: no data. estimated in 20% (higher in gold mining, lower in diamond mining) → 70,000
Gold: Half of 300,000 → 150,000

Government of Sierra Leone: Artisanal Mining Policy for Sierra Leone (http://www.nma.gov.sl/wp-content/uploads/2019/05/Artisanal-Mining-Policy-for-Sierra-Leone.pdf):

Artisanal mining is ongoing in more than half of the country’s 190 Chiefdoms. Artisanal mining is primarily for diamonds and gold although some coltan and zircon are mined. ... Alluvial diamond deposits are depleting; artisanal miners experience diminishing returns as they nonetheless continue to mine areas in hope of finding diamonds. Many have shifted to gold mining. Also, the emerging motor-cycle taxi business is attracting young men away from artisanal mining. Although no empirical data on the number of people involved in artisanal mining has been published, it is estimated that artisanal mining and related activities provides livelihood support to **at least 300,000** Sierra Leoneans and that upwards of 10% of Sierra Leoneans are impacted by artisanal diamond mining operations."

(ARM-18), Table Annex 3: 200,000
Quoting Hilson & Hilson (2015): https://www.theigc.org/wp-content/uploads/2015/04/Hilson-Hilson-2015-Working-Paper.pdf

(IGF-18): Table 3

Directly working in ASM: 300,000
Estimated number of dependents: 1,800,000
Main Minerals: Gold, Diamonds

(HIL-16):

Directly working in ASM: 300,000
Estimated number of dependents: 1,800,000

(UBC-14): Gold-only data produced by statistic modelling:

Expected ASM population: 437,000 
Estimated ASM gold production: 3.5 t/a

Cartier, Bürge 2011 - Agriculture and Artisanal Gold Mining: https://www.researchgate.net/publication/254456911_Agriculture_and_artisanal_gold_mining_in_Sierra_Leone_Alternatives_or_complements : “Bermúdez-Lugo (2010) estimated that there are 120,000 diamond and gold artisanal miners in Sierra Leone; but in reality, this figure is much larger.”

(ILO-99): Employment: 30,000 - 40,000
Number of mines: n/a
Illegal mines: n/a

Videos:
https://www.youtube.com/playlist?list=PL91CF7335E6F97A63

Articles:
http://www.nma.gov.sl/wp-content/uploads/2019/05/Artisanal-Mining-Policy-for-Sierra-Leone.pdf
https://www.theigc.org/wp-content/uploads/2015/04/Hilson-Hilson-2015-Working-Paper.pdf
https://www.researchgate.net/publication/254456911_Agriculture_and_artisanal_gold_mining_in_Sierra_Leone_Alternatives_or_complements