Assay Services for Mining: Methods, Costs, Turnaround

Mineral assay and testing at a glance: methods, costs and turnaround

Assay services measure how much of a metal or mineral a sample holds. Gold fire assay cost US$45 to US$55 per sample for the analysis alone at Hazen Research in Colorado (Hazen fee schedule effective 1 July 2026). Crushing and grinding add about US$30 per sample, a multi-element scan adds US$155 or more, and routine results at that lab take 15 to 20 business days. Other labs quote their own prices and dates, so the sections below show what published schedules say, how the methods differ, and how to compare labs before you ship a single bag.

Three terms come up in every quote. A grade is the amount of metal in the rock, written in grams per tonne (g/t) or parts per million (ppm); the two units are the same number. A detection limit is the smallest amount a method can report. A finish is the instrument that measures the metal after the sample has been dissolved or fused. Most price differences between methods come from the finish and from the weight of sample the lab must process.

Gold and silver assay methods compared

Fire assay is the reference method for gold. ALS describes it as the benchmark since the mid-twentieth century: the pulverised sample is mixed with a lead-oxide flux, melted above 1,000 degrees Celsius so the gold collects in a lead button, and the button is cupelled to leave a small doré bead of precious metal (ALS, gold by fire assay). SGS describes the same industry-standard process for gold and platinum group elements in drill core, soil and chip samples, with the bead finished by atomic absorption, ICP-OES, ICP-MS or neutron activation (SGS Minerals fire assay brochure).

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Fire assay: 30 g against 50 g charge

C$ per sample, ALS Geochemistry schedule of services and fees, 2022 (CAD)

The finish decides the reporting range, so pick it from the grade you expect. The table lists ALS method codes because they are published with ranges and prices; other labs use their own codes for the same ideas.

Ranges and codes come from the ALS fire assay page; fees come from the ALS schedule hosted by the Newfoundland and Labrador government (ALS Geochemistry schedule of services and fees, 2022, CAD) and from the Hazen schedule above. Prices change, and the 2022 edition is a guide to relative cost, not a quote.

Fire assay or aqua regia for gold

Many exploration packages report gold twice: once by fire assay and once inside a multi-element aqua regia or four-acid run. The two numbers can differ because the sample portions differ. Bureau Veritas data show good agreement between a 50 g fire assay and a 0.5 g aqua regia leach in one data set, with a small positive bias toward fire assay, which is a total digestion while aqua regia is partial. In a second set that held coarse gold, aqua regia results scattered and the bias grew with grade, because one grain of native gold has a hundred times more effect in a 0.5 g portion than in a 50 g one (Bureau Veritas, comparing gold values determined by fire assay and aqua regia). For soils and sediments, the Association of Applied Geochemists published a paper on choosing between the two (Leybourne and Rice, EXPLORE 158). Bureau Veritas calls fire assay the benchmark technique for quantifying gold and aqua regia the usual leach for pathfinder and vectoring elements, so the fire assay number is normally the one reported as the gold grade.

Multi-element, XRF and mineralogy methods: when you need more than one grade

In geological assay work, copper, zinc, lithium, rare earths and most pathfinder elements are normally measured by digesting the powder in acid and reading the solution on an ICP instrument. ALS lists a four-acid ICP-AES package (ME-ICP61) covering 33 elements for C$20.15 and a four-acid ICP-MS package (ME-MS61) covering 48 elements for C$40.95 in its 2022 schedule. Four-acid digestion dissolves most minerals, but ALS notes that barite, rare earth oxides, columbite-tantalite and some titanium, tin and tungsten minerals may not dissolve fully, so check which minerals your target holds.

At Hazen Research, an ICP-OES scan of about 31 elements by four-acid digestion costs US$155 plus US$20 for the digestion, an ICP-MS precious metals scan costs US$130, and a semi-quantitative X-ray fluorescence scan on loose powder costs US$65. XRF with borate fusion is US$130 and reports major oxides plus a few trace elements, but Hazen states it is not suitable for sulfide content above 1% or for precious metals (Hazen fee schedule, July 2026).

Mineralogy answers a different question: which minerals hold the metal, and how easily do they separate in a mill. The same Hazen schedule lists semi-quantitative X-ray diffraction (XRD) at US$300, quantitative XRD at US$375 (3 to 5 g of material), polarizing light microscopy at US$875, and automated QEMSCAN scanning electron microscopy by quote. Those results feed processing tests and, later, the value of a project; our note on mineral asset valuation and mineral separation looks at both topics.

Handheld XRF in the field

Portable XRF gives a reading in seconds and suits drill-core logging and ore sorting, but it is a screening tool for gold. ALS reports that the best-case detection limits for common pathfinder elements by XRF are 1 to 10 ppm, against 0.01 to 1 ppm for a typical soil package by acid digestion and ICP-MS, and that arsenic, tungsten and zinc can give false gold readings (ALS technical note on portable XRF).

Automated testing systems and lab software

Automation now sits at several points in the chain. ALS and Intertek both list sample-tracking portals for clients (WebTrieve and LabTrak), the ALS schedule offers a mobile app that tracks samples and sends alerts, and Intertek lists robotics and automation among its minerals services (Intertek, mineral assay and testing). Automated mineralogy such as QEMSCAN and bulk methods such as PhotonAssay on 500 g charges are two examples of instrument-led testing. For a mining company running its own laboratory, the software layer is a laboratory information management system, which logs each sample, method, result and quality-control check. The short video below shows soil geochemistry and ICP assays used alongside satellite targeting on copper and gold ground in British Columbia.

▶ Satellite targeting and soil geochemistry with ICP assays on copper and gold ground in British Columbia. · 3:11

What assay services cost per sample

Published fee schedules are the best price evidence, because quotes by email cannot be checked. The chart shows Hazen Research’s fee per sample for eight services. Of these eight services, gold by fire assay is the cheapest; mineralogy by microscope costs almost twenty times as much as the gravimetric gold line. All figures are in US dollars per sample and exclude sample preparation.

Chart

Fee per sample by method at one US laboratory

US$ per sample, Hazen Research fee schedule effective 1 July 2026; solids may need preparation (US$30) or digestion (US$20) on top

Weight matters as much as method. ALS bills crushing by the kilogram (fine crushing to 70% passing 2 mm is C$3.80 plus C$0.75 per kg) and pulverising a split of up to 250 g to 85% passing 75 microns is C$5.70, so ALS’s PREP-31 package (crush, riffle split to 250 g, pulverise, sample login) is C$9.95 plus C$1.15 per kg, so a 2 kg drill sample costs C$12.25 to prepare before any analysis. Hazen charges US$30 for the first 2 lb of rock and US$3 for each additional pound. Fire assay at ALS comes in 30 g and 50 g charges, and the bigger charge costs about C$4.00 to C$5.60 more. A larger charge helps when gold is coarse, because it holds more grains.

Extras that change the invoice

Read the general-information pages of any schedule. Hazen adds a 100% surcharge for priority service, a 25% surcharge (minimum US$50) for a formal report with quality-control data, and US$50 per month per order for samples left uncollected after 100 business days. It returns samples 30 days after reporting once invoices are paid, and states that results represent only the samples analysed. Hazen also offers discounts on large projects by quotation. Ask any lab whether batch administration, environmental or reject-disposal fees apply on top of the method price.

What a full drill-sample package costs

A drill program usually buys preparation, a gold assay and a multi-element package for every sample, plus quality-control samples that the geologist adds to each batch. The chart adds up the published ALS 2022 prices for one 2 kg sample: preparation of C$12.25 (PREP-31 package) plus each analytical package. Adding a four-acid ICP-MS scan to a gold assay more than doubles the cost of a sample.

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Preparation plus analysis for one 2 kg sample

C$ per sample; ALS 2022 schedule, preparation C$12.25 (PREP-31 at 9.95 + 1.15 per kg) plus the package shown

The calculator below turns those fees into a program budget. Its defaults use the Hazen July 2026 prices (US$30 preparation, US$55 gold by AA finish, and US$175 for a four-acid ICP-OES scan with digestion) and a 15% share of quality-control samples. Replace every fee with the figures from your own quote.

How long assay results take

Turnaround depends on the preparation queue, the method, the batch size and whether samples need a re-assay. Hazen reports routine analyses by email in 15 to 20 business days, offers priority service at a 100% surcharge with typical delivery within ten working days, and does not guarantee either figure. Over-range samples add time: an AAS fire assay that reports up to 10 ppm gold must be re-run by an ore-grade or gravimetric method when a sample exceeds the limit, which is why ALS lists several finishes with overlapping ranges.

Instruments change the clock for part of the work. PhotonAssay measures a 500 g charge of crushed sample, a larger portion than fire assay, and no source here gives a turnaround for it. Mine-site laboratories shorten shipping and queues for ore-control samples. For exploration batches shipped to a commercial lab, ask for a delivery date in writing when the lab confirms receipt, and ask what happens to the date if samples fail quality control and need repeating.

Assay laboratories compared: facts about named labs

The table lists labs and what their own documents or accreditation registers state. It is not a ranking and not an endorsement, and a lab missing from it is not worse. Details change, so open the linked register before you rely on a scope.

Sources: Bureau Veritas analytical and assay laboratories, the Standards Council of Canada scope for Bureau Veritas Vancouver, the NATA scope for BV Minerals Perth, the IAS certificate for American Assay Laboratories, and the Perth Mint analytical services page.

How to read assay results in mining

An assay certificate lists, for each sample, the method code, the element, the unit and the result. Check four things on every one.

• Units. Gold is usually in ppm or g/t. One troy ounce per short ton equals about 34.3 g/t, so a result of 3.4 g/t is roughly 0.1 troy ounce per ton. Base metals are often in percent, with 1% equal to 10,000 ppm.
• Detection limits. A result shown as less than the lower limit means the method could not measure the metal at that level, not that none is there. ALS reports gold by AAS fire assay from 0.005 ppm and by ICP finish from 0.001 ppm.
• Upper limits. A result at the top of the range, such as 10 ppm for trace-level fire assay, is a floor, not the true grade. The lab should re-assay it by an ore-grade or gravimetric method.
• Method and digestion. Partial digestions such as aqua regia and total methods such as fire assay can give different numbers for the same rock, as described above.

Standards, blanks and duplicates

Reliable results need controls inserted into the batch. Certified reference materials (standards) show whether the lab reads a known grade correctly, blanks show contamination, and duplicates show how repeatable the sampling and the analysis are. In a 2007 article for the Canadian Institute of Mining, two AMEC geologists wrote that a quality-control program usually costs no more than one to two percent of total exploration cost, and that AMEC regards sole reliance on a laboratory’s internal controls as unacceptable because labs commonly report the checks that pass (Simon and Gosson, Canadian Institute of Mining). The same article notes that Canada’s disclosure rule NI 43-101 requires a company to describe its quality assurance and control measures when it reports exploration results. Hazen’s schedule shows the same practice from the lab side: it keeps certified standards for many matrices and offers a quality-control data report at an extra 25%.

▶ A mineral management system that keeps maps, samples and targets in one place. · 3:21

Sampling and sample preparation: where assay error starts

Most of the uncertainty in a gold result comes before the instrument. A 30 g charge is a tiny piece of a 2 kg drill sample, and when gold sits in a few coarse grains the pulp can differ from its neighbour by a wide margin. Three habits reduce the error: crush and pulverise to a consistent fineness (ALS pulverises to 85% passing 75 microns), split the sample with a riffle or rotary splitter, and send enough material. ALS asks clients to submit at least three times the nominal sample weight, and Hazen requires 30 g for fire assay while asking for 100 g.

Infographic

From field sample to assay certificate in 6 steps

1. 1Collect and logTake a representative sample, label it and record the location and the chain of custody.
2. 2Insert controlsAdd standards, blanks and duplicates at set positions in each batch.
3. 3Crush and splitCrush to a set fineness and split with a riffle or rotary splitter.
4. 4PulveriseGrind a split to about 85% passing 75 microns so the charge is uniform.
5. 5Fuse or digest and measureFire assay a 30 g or 50 g charge, or digest in acid, then read on AAS, ICP or XRF.
6. 6Check and reportThe lab checks its controls; you check yours before accepting the certificate.

For ore that may hold coarse gold, a metallic screen assays the whole oversize fraction as well as the fine fraction. ALS lists it at C$75.10 per sample against C$21.75 for a routine fire assay, so use it on selected samples, not every bag.

How to choose an assay lab: eight checks before you ship samples

1. Accreditation scope. A lab being accredited to ISO/IEC 17025 does not mean your method is covered. Open the scope on the register (Standards Council of Canada, NATA in Australia, the International Accreditation Service in the United States) and find the row for your element, technique and sample type.
2. Method code. Ask for the exact code, sample weight and finish, such as 30 g fire assay with AAS finish, and write it into the purchase order.
3. Detection range. Match the range to the expected grade, and ask which method the lab uses for over-range samples.
4. Preparation. Ask for crushing and pulverising specifications and what is charged per kilogram.
5. Quality control. Ask what the lab reports on its own standards, blanks and duplicates, and tell it where your inserted controls sit.
6. Turnaround. Get a delivery date in writing, and the cost of priority service.
7. Chain of custody and storage. Check how samples are logged, sealed and stored, and how long rejects and pulps are kept. Hazen, for example, returns samples 30 days after reporting.
8. Second lab. Plan to send a share of pulps to an independent lab as a check, and name an umpire lab in your contract.

Gold assay services near me

For a small program or a purchase check on a claim, the nearest lab is often a commercial exploration lab with a drop-off or courier depot. In the United States, examples with published documents include American Assay Laboratories in Sparks, Nevada, and Hazen Research in Golden, Colorado; in Canada and Australia, the Standards Council of Canada and NATA publish scope documents for accredited mineral labs. Our guide to fire assay for gold and finding a gold assay near you goes deeper on the small-sample route, and the note on geochemical analysis methods compares XRF, fusion and assay for rock samples.

Screening ground before you pay for assays

Assays cost money per sample, so where you sample matters. Satellite imagery cannot tell you a grade, but it can map iron-oxide staining, clay alteration and structures, which helps place soil lines and rock chips on the ground most likely to carry metal. Farmonaut’s satellite-based mineral detection works from an area file such as a KML or KMZ and returns exploration targets that sit ahead of any assay or resource estimate. If you plan a sampling program and want to see what it would cover, you can request a quote or contact the team. For survey sequencing around a first season, see our guide to induced polarization survey sequencing.

▶ How satellites help find gold: they map the rock around it, not the metal itself. · 4:25

Frequently asked questions

What is an assay in mining?

An assay is a laboratory measurement of how much of a metal or mineral a sample holds. For gold, the result is usually reported in grams per tonne after fire assay. Assays drive resource estimates, so mining companies disclose their quality-control program alongside them.

How much does a gold assay cost?

Analysis alone was US$45 for fire assay with a gravimetric finish and US$55 with an AA finish in Hazen Research’s schedule effective July 2026. ALS listed C$21.75 to C$27.95 for 30 g fire assay in its 2022 Canadian-dollar schedule. Preparation, batch fees and any priority surcharge come on top.

How long does a fire assay take?

Delivery is quoted in weeks, not hours: Hazen states 15 to 20 business days for routine analyses and about ten working days with priority service at a 100% surcharge, without a guarantee. Other labs quote their own times, so ask for a date in writing.

What is the difference between fire assay and ICP?

Fire assay is a total fusion method used to concentrate gold and platinum group metals into a bead before measurement. ICP is an instrument that reads many elements in an acid solution. A fire assay can end with an ICP finish, and a four-acid ICP package measures dozens of elements but may not dissolve every mineral.

What does an assayer do?

An assayer prepares and analyses samples to find the content of metals, working in an exploration lab, a mine-site lab or a refinery. Refinery assayers, such as those at The Perth Mint, test doré and bullion, while exploration assayers test rock, soil and drill samples.

How do you assay ore?

Crush the ore, split it, pulverise a representative portion to a fine powder, weigh a charge of 30 g or 50 g, fuse it with flux, cupel the lead button and measure the bead. The same steps appear in the flow chart above, and the QC samples go in before the batch is sent.

Can handheld XRF replace a lab assay?

For gold, no. ALS reports best-case detection limits of 1 to 10 ppm for pathfinder elements by XRF and warns of interferences from arsenic, tungsten and zinc. It suits screening and logging, with lab assays confirming the grade.

What are standards, blanks and duplicates?

Standards are samples with a certified grade, blanks are barren material that should read near zero, and duplicates are repeat samples that test repeatability. Inserted into each batch, they show whether the lab and the sampling are reliable.

What does mining laboratory management involve?

It covers sample receipt and chain of custody, preparation and analysis queues, calibration and quality-control charts, accreditation records and data delivery. Many labs give clients a portal for tracking, and a laboratory information management system holds the records.

How many samples should I send?

It depends on the program, but the cost scales with sample count and with the share of control samples. Use the calculator above with your own fees, and keep a fixed share of standards, blanks and duplicates in every batch.

Fees and accreditation details were taken from the documents linked above and change over time. This page is for information only; confirm methods, prices and scope with the laboratory before you submit samples.