This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
Although Crono must be in your party to use all of the "normal" Triple
Techs, there are items hidden in this game which will give your
characters secret Triple Techs.
These items, called "rocks," fit into your characters' accessory
Try searching for rocks in the following areas: Kajar, Black Omen,
Laruba Ruins, the Giant's Claw, and the Denadoro Mountains.