How to Read an SGS Certificate of Analysis for Antimony Ore Before You Pay

The number that matters most on an antimony ore COA is the Sb percentage. That's the figure your price is built on. But the grade line alone isn't enough to pay against — you also need to know what was sampled, how it was prepared, which method ran the assay, and what penalty elements came back.

Here's how to read the whole document, line by line, before you release any money.

What the SGS certificate of analysis for antimony actually tells you

A proper SGS certificate of analysis antimony document is tied to a specific lot. Not to a mine, not to a "typical" grade. To the physical parcel sitting at a particular point in the chain.

So the first thing you check is the identity block. Lot or batch number, description of the material, the client, and the date. If the certificate doesn't name the lot you're being offered, it's describing something else.

Then the sampling and preparation notes. This is where most buyers skip ahead — don't. A grade is only as good as the sample it came from. You want to see how the sample was taken, whether it was crushed and split, dried, and to what mesh it was pulped before analysis. Standard SGS practice crushes and pulverises, then splits down to a representative portion. If that section is blank or vague, ask for it.

Next, the method. For antimony you'll usually see a titrimetric method for the main Sb figure, sometimes XRF for a quick read, and ICP or AAS for trace elements. The method matters because it tells you the precision you can expect. Titration on a properly prepared pulp is the one most antimony buyers want to see for the headline Sb number.

And then the results table itself.

The lines on a Sb ore COA, and what each one means

Here's a plain reading of a typical antimony ore assay check. Your exact table will vary — these are the lines buyers ask about most.

Two things trip people up here.

First, dry basis versus as-received. The Sb figure you pay on should be on a dry basis, with moisture determined separately and deducted when the material is weighed. If a certificate quotes Sb without saying which basis, confirm it in writing before you treat it as final.

Second, penalty elements. For antimony, arsenic is the one most buyers flag, because it carries through into downstream products. Whether arsenic triggers a deduction — and at what threshold — is a commercial term in your contract, not something SGS decides. The lab reports the number. You and the seller agree what it costs. So make sure your contract spells out the penalty table before loading, not after.

How to check the certificate is genuine and current

A scan of a certificate is easy to send. Harder to verify. A few checks:

• Confirm the certificate carries a report number, the issuing SGS office, and an authorised signature or electronic equivalent.
• Check the date against your shipment window. A certificate from an old lot doesn't describe the parcel you're buying now.
• Match the lot number on the COA to the lot number on the offer and, later, the shipping documents. They should be the same lot all the way through.
• If anything looks off, you can ask SGS directly to confirm a report they issued. That's the point of using an independent lab.

Honestly, the biggest mistake I see is buyers treating a "typical analysis" as if it were a lot certificate. A typical analysis is a sales sheet. A lot COA is evidence about the material you're actually paying for. Don't confuse the two.

Your own sampling and inspection rights

You don't have to take one lab's word for it, and you shouldn't have to. With GBX antimony ore, each lot is sampled and analysed by SGS Pakistan and sold against that SGS certificate of analysis. Buyers may also test a sample in their own laboratory, and may appoint SGS or their own inspector at loading.

That's the arrangement you want on any ore purchase. So when you set up a contract, pin down:

• Who takes the official sample, and where (at loading is common).
• How the sample is split — one portion to the seller, one to the buyer, one sealed as an umpire sample.
• Which lab is the referee if your result and the seller's result disagree beyond an agreed tolerance.
• The settlement rule: whose figure the invoice is based on, or whether you split the difference.

Umpire clauses exist because two honest labs can return slightly different numbers on the same material. That's normal. The question is who you both trust to break the tie, and you agree that name up front.

Before you release payment, run this list

• The lot number on the COA matches the offer and the shipping documents.
• Sb % is stated on a dry basis, with moisture reported separately.
• The sampling and preparation method is described, not blank.
• The assay method is named (titration, XRF, ICP/AAS).
• Penalty elements — arsenic especially — are reported and matched against your contract's penalty table.
• The certificate carries an SGS report number and issuing office.
• Your inspection and independent testing rights are written into the contract, not just promised.
• The settlement and umpire terms are agreed before loading.

Get those eight right and you're paying against evidence, not a promise.

Want the current specification and availability on a specific lot? Request a quote on the antimony ore page, or message WhatsApp +92 300 3644444 with your required Sb range and crush size.