Bit of mountaineering equipment touching stone first (5)

I believe the answer is:
piton
'bit of mountaineering equipment' is the definition.
'piton' can be an answer for 'equipment' (piton is a kind of equipment). I am not sure about the 'bit of mountaineering' bit.
'touching stone first' is the wordplay.
'touching' becomes 'on'.
'stone' becomes 'pit' (synonyms).
'first' is a charade indicator (letters next to each other).
'on' after 'pit' is 'PITON'.
Can you help me to learn more?
(Other definitions for piton that I've seen before include "It helps the climber" , "Metal spike used in rock climbing" , "Climber's iron peg" , "Peg driven into rock in mountain climbing" , "Climber's spike" .)
