Tetradymite
is a mineral consisting of bismuth, tellurium and sulfide, Bi2Te2S, also known as telluric bismuth. If sulfur is absent the mineral is tellurobismuthite and the formula is then Bi2Te3. Traces of selenium are usually present.
Crystals are rhombohedral, but are rarely distinctly developed; they are twinned together in groups of four; hence the name of the mineral, from the Greek for fourfold. There is a perfect cleavage parallel to the basal plane and the mineral usually occurs in foliated masses of irregular outline. The color is steel-grey, and the lustre metallic and brilliant. The mineral is very soft (H = 1.5 - 2) and marks paper. The specific gravity is 7.2 to 7.9.
The type locality is Zupkov (Zsubko; Schubkau), Stredoslovenský Kraj, Slovak Republic where it was reported in 1831. It was first found, in 1815, at Telemark in Norway; crystals are from Schubkau. It often occurs in quartz associated with native gold.
Tetrahedrite is a copper antimony sulfosalt mineral with formula: (Cu,Fe)12Sb4S13. It is the antimony endmember of the continuous solid solution series with arsenic bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, the antimony rich phase is more common. Other elements also substitute in the structure, most notably iron and zinc along with less common silver, mercury and lead. Bismuth also substitutes for the antimony site and bismuthian tetrahedrite or annivite is a recognized variety. The related, silver dominant, mineral species freibergite, although rare, is notable in that it can contain up to 18% silver.
Tetrahedrite gets its name from the distinctive tetrahedron shaped cubic crystals. The mineral usually occurs in massive form, it is a steel grey to black metallic mineral with Mohs hardness of 3.5 to 4 and specific gravity of 4.6 to 5.2.
It occurs in low to moderate temperature hydrothermal veins and in some contact metamorphic deposits. It is a minor ore of copper and associated metals. It was first described in 1845 for occurrences in Freiberg, Saxony, Germany.

Thenardite is an anhydrous sodium sulfate mineral, Na2SO4 which occurs in arid evaporite environments. It also occurs in dry caves and old mine workings as an efflorescence and as a crusty deposit around fumaroles. It occurs in volcanic caves on Mt. Etna, Italy and was named after the French chemist, Louis Jacques Thenard (1777-1826).
Thenardite crystallizes in the orthorhombic system and often forms yellowish, reddish to grey white prismatic crystals although usually in massive crust deposits. It has a hardness of 2.5 - 3 and a specific gravity of 2.7. Thenardite is fluorescent, white in shortwave and yellow-green in longwave UV radiation.
Thenardite samples will gradually absorb water and convert to the mineral mirabilite,
Tin is a chemical element with the symbol Sn (Latin: Stannum) and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as tin dioxide, SnO2. This silvery, malleable poor metal is not easily oxidized in air, and is used to coat other metals to prevent corrosion. It is used in many alloys, most notably bronze, pewter alloys (from 85% to 99% tin), and tin/lead soft solders typically containing 60% or more of tin.