The Mount Pleasant tin deposit in New Brunswick is unusually complex and contains a wide variety of minerals. The tin-bearing minerals are cassiterite and stannite. Cassiterite is the chief tin mineral and it occurs as disseminations in mineralized rock fluorite
masses and sulphide veins. The cassiterite in the mineralized rock and sulphide veins occurs as small grains, whereas that in the fluorite masses is present as relatively large grains. Stannite was found mainly as irregular grains and minute inclusions in sphalerite and arsenopyrite. Sphaltt rite is
the most abundant ore mineral. It is generally black and contains minute exsolution bodies of chalcopyrite, stannite and pyrrhotite. Analyses of sphalerite concentrates give Zn 45.0 to 48.90%, Fe 7.8 to 13.1%, Cu 1.3 to 5.2%, Sn 0.14 to 0.38%, In 0.03 to 0.30%, Cd 0.1 2 to
0.18%,and Mn. 0.06 to 0.08%. Other minerals in the deposit are: rutile, wolfrarnite, scheelite, hematite, chalcocite, tennantite, covellite, galena, molybdenite, bismuthinite; wittichenite, a\rsenopyrite, glaucoclot, pyrite, marcasite, pyrrhotite, native bismuth, native gold, quartz,
feldspar, topaz, zircon, siderite, calcite, fluorite, biotite, sericite, chlorite, kaolinite, dickite, hydrornica, goethite, scorodite, arseno-bismite, and malachite. Sphalerite geothermornetry indicates that the depositional temperatures of sphalerite fall between 335°C and 700°C, and
arsenopyrite geothermornetry gives depositional temperatures up to 500 °C.