In the harvest scripts. Example. In Mining.cs, line 33 (Mining for Ore and Stone region)
#region Mining for ore and stone
HarvestDefinition oreAndStone = OreAndStone = new HarvestDefinition();
// Resource banks are every 8x8 tiles
oreAndStone.BankWidth = 8;
oreAndStone.BankHeight = 8;
// Every bank holds from 10 to 34 ore
oreAndStone.MinTotal = 10;
oreAndStone.MaxTotal = 34;
// A resource bank will respawn its content every 10 to 20 minutes
oreAndStone.MinRespawn = TimeSpan.FromMinutes(10.0); <<<
oreAndStone.MaxRespawn = TimeSpan.FromMinutes(20.0); <<<
// Skill checking is done on the Mining skill
oreAndStone.Skill = SkillName.Mining;
// Set the list of harvestable tiles
oreAndStone.Tiles = m_MountainAndCaveTiles;