Ironwood

Ironwood is the shielded pool Zcash introduced with the NU6.3 network upgrade, activated on Mainnet on July 28, 2026 (block height 3,428,143). It reuses and extends Orchard's own cryptographic design rather than replacing it with something unrelated — Ironwood is best thought of as a new, hardened pool within the same Orchard protocol family, not a separate system.

Ironwood exists because a soundness flaw was found in Orchard's proof circuit in 2026. Zcash shipped a fix quickly, but since a large share of ZEC was already held in Orchard when the flaw was fixed, the network introduced a freshly built pool — with formally verified proof circuits — to fully restore confidence in the shielded supply going forward. Existing Orchard holders aren't moved automatically; the protocol encourages moving funds to Ironwood over time, and Orchard itself still works for spending, just not for new deposits.

Today, Ironwood is where new shielded activity on Zcash goes.