[Regarding a piece of] tamei iron that one mixed with [a piece of] tahor iron, if the majority is from the tamei [source, the newly formed utensil] is tamei. And if the majority is from the tahor [source, the utensil] is tahor. [If it is] half and half, it is tamei. And the same applies [to a utensil made] from chalama and cattle dung. [A door bolt with] a knob is tamei. But [if it is] plated, it is tahor. A pin tumbler and a bolt are tamei. And [regarding] a [door bolt with a] knob, R’ Yehoshua says: [One may only] drag it from this door and hang it on another one on the Sabbath. R’ Tarfon says: It is like all [other] utensils, and may be carried within a courtyard.