Goods whose supply has a natural upper limit in what's easily obtainable (given current methods and infra) and no easy substitutes in their use up the supply ch

Goods whose supply has a natural upper limit in what's easily obtainable (given current methods and infra) and no easy substitutes in their use up the supply chain often have price spikes when (non-spiking) marginal demand suddenly bumps into that limit ... or else when there's a sudden limitation in the ability to deliver the usual supply of the good. Neither of these is a demand spike, per se.