(a) On an outline map of Nigeria, locate and name one area noted for each of the following: (i) tin mining; (ii) limestone mining; (iii) thermal power stati...

(a) Location of mining and power areas on an outline map of Nigeria

On the outline map, mark and label the following named areas:

• (i) Tin mining: Jos Plateau (around Jos, Bukuru and Barkin Ladi) in Plateau State.
• (ii) Limestone mining: Ewekoro (Ogun State), or Nkalagu (Ebonyi State), or Sokoto and Yandev.
• (iii) Thermal power station: Egbin (near Lagos), or Afam (Rivers State), or Ughelli/Delta, or Sapele.
• (iv) Oil refinery: Port Harcourt (Rivers State), or Warri (Delta State), or Kaduna (Kaduna State).
• (v) Hydro-electric power station: Kainji Dam on the River Niger (Niger State), or Jebba, or Shiroro.

Each point should be located in its correct relative position, with the coastline, the confluence of the Niger and Benue, and state boundaries shown for orientation. A key/legend should distinguish mining sites from power stations.

(b) Method of mining tin in Nigeria

Tin in Nigeria occurs mainly as cassiterite in alluvial (placer) deposits on the Jos Plateau, so it is worked chiefly by open-cast and hydraulic (surface) methods rather than deep shafts.

1. The overlying soil and rock (overburden) covering the tin-bearing gravel is first stripped off using bulldozers, draglines or manual labour.
2. The exposed tin-bearing gravel is then broken up and washed. In hydraulic mining, powerful jets of water are directed at the gravel to break it and wash it into channels.
3. The muddy mixture of water and gravel (slurry) is passed through sluices, jigs and washing pans, where the heavier cassiterite settles and is separated from the lighter waste sand by gravity.
4. The concentrated cassiterite is collected, dried and further purified before being smelted to obtain metallic tin.

Small-scale miners also use simple panning in streams, while larger firms use dredges in the flooded workings.

(c) Four ways minerals are of economic importance to Nigeria

• Source of government revenue and foreign exchange: the export of petroleum and solid minerals earns large amounts of foreign currency and taxes.
• Employment: mining, refining and allied services provide jobs for many people, raising incomes and living standards.
• Industrial raw materials: limestone feeds cement factories, tin and columbite supply metal industries, and crude oil feeds refineries and petrochemical plants.
• Infrastructural development: mining areas attract roads, railways, electricity and towns, opening up otherwise remote regions.
• Energy supply: petroleum, natural gas and coal provide power for industries, homes and transport.