Proof of work · SHA-256 · Bitcoin Core lineage
Mine Spearmint. Rewards to your own address.
Spearmint is a SHA-256 proof-of-work coin forked directly from Bitcoin Core v29.0. Connect SHA-256 hardware directly to the network, solo or through Spearmint Mining. Your keys. Your address. No hosted wallet.
Pre-launch. No mainnet yet, no token sale, no exchange listing, and the mining service is not open. Figures marked proposed are fixed at the genesis block and not before.
Four ways in
Two of these are about the network, which nobody owns. Two are about Spearmint Mining, the pool infrastructure Instant Access operates. The site keeps them apart on purpose.
Learn about Spearmint
A SHA-256 coin with per-block difficulty retargeting, depth-tiered finality, a fixed 210 million cap, and a halving schedule published before genesis. The economic policy is the reference.
Run a node
Spearmint Core is Bitcoin Core with changed chain parameters. Build it, verify the rules yourself, mine solo against your own node if you want to. The network is operated by whoever runs it.
Start mining
Point any SHA-256 miner at the pool with your own Spearmint address as the username. Shares are credited to that address; mature block rewards are apportioned and paid to it automatically.
View network statistics
Block height, hashrate, difficulty, recent blocks, node counts, and pool concentration — every figure checkable against your own node. Live at launch.
A mining service, and only that
Computing-power contributors collectively mine Spearmint blocks. When a block reward is earned, Spearmint Mining calculates each participating miner's share and distributes the applicable mining reward to the Spearmint address that miner supplied. Nothing else happens here.
No hosted wallet
You mine with an address you already control. The service never creates one for you, never holds your keys, and never asks for them.
No deposits
The only thing that enters the pool from a miner is computational work. There is no deposit address, no way to send SPMTC, BTC, or anything else to the service.
No transfers, no exchange
No send, transfer, swap, buy, or sell. No moving rewards between miners. No conversion to another coin or to dollars. Rewards go out to your address, automatically.
| Parameter | Value |
|---|---|
| Hardware | Any SHA-256 ASIC |
| Protocol | Stratum (TCP and TLS) |
| Login | payout address . worker |
| Reward methodology | PPLNS |
| Pool fee | 1% of block rewards |
| Block maturity | 100 confirmations |
| Payout run | daily, automatic, ≥ 1 SPMTC |
What is actually different here
Four claims, each of which you can check against something published rather than asserted.
Bitcoin Core, not a rewrite
The consensus code is Bitcoin Core v29.0 with changed chain parameters. Nothing novel sits in the part of the system where novelty is most expensive to get wrong.
Parameters before launch
Block target, reward, cap, and halving cadence are on the economic policy page while they can still be argued with. They become immutable at the genesis block.
A build log with the failures in it
The log records a genesis-mining script that broke, the exact traceback, and the fix. A log that only contains successes is a brochure.
Identifiable stewardship
Spearmint is directed by Instant Access, a named company in Pennsylvania, rather than a pseudonymous team. Operation of the network remains decentralised; the company runs one pool, not the chain.
The 51% problem, stated plainly
A new SHA-256 chain starts with a small fraction of the hash rate that already exists on Bitcoin. Anyone who can rent enough of it can rewrite recent history. Spearmint's answer is two mechanisms, neither of which is a novel cryptographic claim.
Aggressive difficulty retargeting
Difficulty is recalculated every block rather than every 2,016. Hash rate that arrives suddenly meets a difficulty that rises to meet it within blocks, which removes most of the profit from a short rented attack.
Delayed block finality
Confirmation depth scales with transaction value. Small payments settle quickly; high-value settlement waits deeper, so a reorg deep enough to matter has to be sustained rather than momentary.
Fixed cap, front-loaded decay
210 million SPMTC, all of it issued through mining. The reward halves every six months for the first five years, then annually. These are the supply rules, stated as facts; they are not a forecast of anything.
| Parameter | Value |
|---|---|
| Total supply | 210,000,000 SPMTC |
| Initial block reward | 50 SPMTC |
| Block target | 30 s |
| Blocks per year | 1,051,200 |
| Halving cadence, years 0–5 | 6 months |
| Halving cadence, year 5 onward | 12 months |
| Pre-launch acquisition | 8% · 16,800,000 SPMTC |
Changes happen in public or not at all
There is no token-weighted voting and no treasury. Monetary policy is fixed in code at genesis, which removes most of the levers that governance attacks aim at. The mining service has its own version of this rule.
Signed and reproducible
Binaries ship with SHA-256 hashes and build steps you can repeat to get the same output.
Written down first
Parameter changes go through a published proposal with a rationale and a changelog entry. Pool fee or methodology changes get 30 days' notice.
Some features need a lawyer first
Hosted wallets, deposits, transfers, swaps and the rest are on a published list that no developer may implement without a new legal review.
Where the work actually is
The early-2026 launch window did not hold. Here is what has been done, what is being done now, and what the current working assumption is.
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Oct 2025 → 2026 · done
Foundations
Bitcoin Core v29.0 built, fork scaffolded, chain identity chosen, genesis mining tooling repaired. Recorded in the build log.
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Sep 2026 → · in progress
Extended security testing
AI tooling has cut the cost of several attacks on a small proof-of-work network. Adversarial simulation of ADR/DBF, review of the consensus additions, and a release-process audit are under way. Meeting notes.
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Sep 2026 · published
Mining service designed in the open
The pool's architecture, payout policy, terminology, legal drafts, and the list of features that must never be added without counsel are all on this site before a single share is accepted. The announcement explains why.
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Before opening
Legal review
Pennsylvania's 2025 amendments to its money-transmitter law, FinCEN's mining-pool guidance, and OFAC obligations are being reviewed by counsel. The open questions are listed. The pool does not open until they are closed.
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2027 · working assumption
Public launch window
Gated on the testing programme and the legal review completing. No date is set; mining endpoints open progressively as thresholds are met.
Questions worth asking
What is Spearmint Core derived from?
Is Spearmint Mining a wallet, an exchange, or a place to buy SPMTC?
How is a 51% attack made harder?
Which miners work?
getblocktemplate and keeps RPC on localhost. You can also mine solo against your own node — see Run a node.When can I run my own node or start mining?
Is there a presale, airdrop, or token sale?
Is this financial advice or an investment product?
Who is responsible if something breaks?
Hear about it when something actually happens
Launch decisions, mining-service status, policy changes with notice. Email only, double opt-in, unsubscribe in every message. No price talk.
Double opt-in: nothing is sent until you click the link in the confirmation email. Already on the list? Unsubscribe here. What is stored and why: the announcements page.