No abilities of artifacts can be activated, including mana abilities.

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities, such as equip, are activated abilities and will have colons in their reminder text.

Stony Silence's ability affects only artifacts on the battlefield. Activated abilities that work in other zones (such as cycling) can still be activated. Triggered abilities (starting with "when," "whenever," or "at") are unaffected.