Weight: ½ lb.
Estimated Value (Sane Cost Guide): 250 gp
DMG Value: 101 gp - 500 gp
A mind crystal contains sorcerous potential, allowing a user to apply Metamagic to a spell as you cast it. For the non-sorcerers among us, Metamagic allows you to tweak and alter a spell to better suit your needs, such as extending its duration or increasing its range. While Metamagic is a sorcerer class feature that needs sorcery points to use, mind crystals are single-use items that can be used by anyone who can cast a spell.
A distant mind crystal adds 100 feet to your ranged spells and grants touch spells a range of 30 feet. Depending on the combat encounters you face, you can use these to snipe enemies from afar or to keep yourself away from enemies while hitting them with spells that would normally require risking danger.
Spell suggestions: arcane lock, bane, bestow curse, bless, contagion, inflict wounds, invisibility
Source: Phandelver and Below: The Shattered Obelisk