Gerolamo Pool Records Verified Block on Cardano Preview

A block issued by the GERO stake pool was accepted on Cardano Preview on September 12, 2026, at 06:33 UTC. It was produced in epoch 1418 and contained zero transactions. This is the only GERO block currently identified in public Preview explorer data.

Gerolamo Pool Records a Cardano Preview Block

The block is identified by the following hash:

50de738df07c876dd4700676533a6afaa685afc18dd970739805bb54de9693e3

Cexplorer lists the issuer as GERO, or Gerolamo Pool. The block remained on the Preview chain at the time of verification, with subsequent blocks extending the same chain.

Preview is Cardano’s public testing network and uses test ADA without market value. It allows node developers and stake pool operators to test synchronization, validation and block production without exposing mainnet funds.

No additional GERO blocks have been identified. The available evidence therefore establishes a single accepted block rather than repeated or stable block production.

Gerolamo Advances Beyond Chain Synchronization

The block appeared six days after Harmonic Labs founder Michele Nuzzi reported that Gerolamo had completed a full synchronization of Cardano Preview from genesis to the network tip with validation enabled.

Gerolamo is a lightweight and modular Cardano node and relay implementation written in TypeScript and primarily designed to run on the Bun runtime. Its current components include Handshake, ChainSync and BlockFetch support, peer management, chain storage, transaction submission and a limited Blockfrost-compatible interface.

The software allows infrastructure operators and developers to follow the Cardano chain, store blockchain data, access blocks and UTxOs, submit transactions and integrate Cardano functionality into other applications.

Gerolamo is separate from Gerolamino, Harmonic Labs’ browser-oriented light node initiative. No public evidence indicates that the September 12 block was produced inside a browser.

The project joins other alternative Cardano implementations under active development. Blink Labs’ Dingo is written in Go and has produced blocks on Preview and Preprod, while Amaru is an exploratory Rust implementation capable of synchronizing and operating as a node on Cardano mainnet.

Implementing the same protocol through different programming languages and architectures can expose implementation-specific bugs and identify areas where protocol specifications are incomplete or interpreted differently.

Full Gerolamo Forging Path Remains Undocumented

Gerolamo’s public repository includes networking, chain synchronization, soft body validation and a TypeScript implementation of key evolving signature functionality. Its documentation also states that full Praos leadership functionality is not currently within the documented scope.

Public information does not establish whether leader election, VRF calculation, key evolving signatures, block construction, signing and propagation were all performed entirely within Gerolamo.

An on-chain issuer identifies the stake pool credentials that signed the block, but it does not independently identify every software component used in the production pipeline. The confirmed result is therefore narrower: credentials registered to the GERO pool issued a valid block that was retained by Cardano Preview.

Further verification could include repeated GERO blocks, blocks containing transactions, reliable rollback and fork handling, longer stability testing and operation on Preprod. Mainnet block production would additionally require the complete forging workflow to operate reliably under live ADA-backed staking and production network conditions.

The September 12 chain record establishes one concrete result: GERO issued a valid Cardano Preview block that subsequent nodes accepted and extended. Repeated production and public documentation of the forging path would establish whether Gerolamo is independently performing the complete block producer workflow.