Occurrence of the elements
The elements are all well known, apart from germanium.
Carbon is the seventeenth, and silicon the second most abundant element by weight in the Earth's crust.
Germanium minerals are very rare.
Ge occurs as traces in the ores of other metals and in coal, but it is not well known.
Both Si and Ge are important for making semiconductors and transistors.
Though the abundances of tin and lead are comparatively low, they occur as concentrated ores which are easy to extract.
Both these metals have been well known since before biblical times.
Carbon occurs in large quantities combined with other elements and compounds mainly as coal, crude oil,
and carbonates in rocks such as Calcite (CaCO3), and Magnesite (MgCO3) and Dolomite (MgCO3. CaCO3).
Carbon is also found in the native form. Large amounts of graphite are mined and extremely small quantities
(in tonnage terms) of diamonds are mined too. Both CO2 and CO are important industrially.
CO2 occurs in small quantities in the atmosphere but has a vital
role in the carbon cycle with photosynthesis and respiration.
CO is an important fuel, and forms some interesting carbonyl complexes.
Silicon occurs very widely, as silica SiO2 (sand and quartz), and in a wide variety of silicate minerals and clays.
Germanium is only found as traces in some silver and zinc ores, and in some types of coal.
Tin is mined as cassiterite SnO2, and lead is found as the ore galena PbS.