An unbiased and interesting article on the mining of manganese: DYOR
http://www.insideindonesia.org/community-mining-in-west-timor
"Strengthening benefits, addressing impacts
In some cases, mining activities have been directly beneficial to farming. Manganese absorbs heat and can keep the soil hot and dry, so the removal of manganese rocks from farming land can make it more suitable for growing crops. In one village in South Central Timor, manganese occurs as sheets below the surface so that crop plants cannot penetrate and develop deeper root systems. After mining this land has been converted into productive terraced market gardens. In another location near Kupang, a landholder mined on the edges of a hillside that broadened his rice field so he can now plant more rice each year. "
"Livelihood contributions from mining
Mining activities can be carried out during quieter farming seasons and can also act as a safety net when crops fail. Unlike high-value minerals such as gold, manganese has low commercial value with the average price over the past ten years sitting at around Rp.1000 per kilogram (US$0.08), although it can fluctuate between Rp.500–1500 (US$0.04–0.12) per kilogram. Most households can mine between 10 and 100 kilograms per day, giving an average weekly income of Rp.70,000–700,000 (US$5.60–56) if actively mining every day. Because the price of manganese is low, hard work is required to generate substantial income, and benefits are fairly evenly spread throughout a community. Income from mining can be used to invest into farming livelihoods, by purchasing livestock, seeds and arable land. Other common uses of income from mining include supporting children’s education, improvements to houses and the purchase of motorbikes."
