稀有金屬用MTU作單位,MTU是什麼呢?

From http://digicoll.library.wisc.edu/cgi-bin/EcoNatRes/EcoNatRes-idx?type=div&did=ECONATRES.0056.0993.0059&isize=text
MTU = metric ton unit

From http://www.emis.platts.com/thezone/guides/platts/metals/conversion.html
1 metric ton (mt) = 2204.62 lb
1 metric ton unit (mtu) = 22.046 lb
1 MTU 應該等如 100kg

A British Thermal Unit (BTU) is the amount of heat energy needed to raise the temperature of one pound of water by one degree F.

One BTU is approximately:

1.054-1.060 kilojoule
252–253 cal (calories, small)
0.252–0.253 kcal (kilocalories)
778–782 ft·lbf (foot-pounds-force)