Rune shards can be made by using rune essence or pure essence with a hammer to crack them into small pieces. The shards can then be ground down into rune dust.
Rune shards and rune dust feature in the Garden of Tranquillity quest, where it is revealed that adding the essence to a plant cure potion enhances its potency. This potion is then used to successfully treat the badly diseased vines in Bernald's garden behind his house in Taverley.
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Trivia
While rune dust is created automatically after creating one, rune shards and strengthened plant cure are not.
Along with rune dust and strengthened plant cure, rune shards are one of only three quest items from Garden of Tranquillity that are dropped rather than destroyed.
The player can create rune shards and rune dust without starting Garden of Tranquillity, but nothing interesting happens when attempting to put rune dust into plant cure to create strengthened plant cure.
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