Organ pipe

An organ pipe is a sound-producing element of the pipe organ that resonates at a specific pitch when pressurized air (commonly referred to as wind) is driven through it. Each pipe is tuned to a specific note of the musical scale. A set of organ pipes of similar timbre tuned to a scale is known as a rank or a stop.

Organ pipes are generally made out of either metal or wood. Very rarely, glass, porcelain, plastic, paper, Papier-mâché, or even stone pipes may be seen. A historical organ in the Philippines has pipes made exclusively of bamboo.

Metal pipes are usually made of lead; for increased rigidity it is alloyed with tin along with trace amounts of antimony and copper. The percentage of each metal in the alloy influences the characteristics of the resulting pipe. A high proportion of tin results in a slightly brighter colouring. In addition, high amounts of tin give a gleaming and long-lasting polish, which may be desired if the pipe is clearly visible. The cost of each metal is also a factor, as tin is more expensive than lead. Cost considerations may also lead to the use of the inferior rolled zinc especially for the lower tones that take a lot of material. In addition, pipes have been made of many metals, including copper, aluminium, gold electroplate, silver, brass, and iron.

...
Wikipedia