strength required to mine silver ore?

[KeiKei]

i'm at 71 str and 21q pickaxe and i can barely scratch this rock containing what i believe is silver

how much strength will it require?

[tirioll]

There is no specific level requirement for any particular ore. Mining difficulty is random for every vein you encounter, but generally increases the deeper you go. As far as I know, silver ore is possible on level 2 and deeper.

In Amber client, you can always toggle shift+i and hover over cave walls with shift or ctrl+shift to see the name of the ore. So you can tell if it is silver without even mining it. Wiki is down right now, and "Ores" page there is very useful. But if you have "Hornblende", it is not silver.

[DreadDawson]

you need a better pick. You're soft capping the rocks. If you need to, use a stone axe of a higher quality. It'll take longer to mine, but at least the quality won't be soft capped by the tool.

[MagicManICT]

For silver, it really doesn't matter, anyway, as silver nuggets (and thus bars) are like gold and have no quality.

Also worth noting that different kinds of ores and stone have hardness factors. Some are harder or softer than others, so even in a node of soft rocks, you can hit a different kind of stone or ore and not be able to mine it.