Every procurement team has faced this scenario: a new mineral supplier presents competitive pricing, a professional website, and a data sheet that looks reassuring on paper. The first container arrives — and so does the problem. Elevated iron levels turn a glass melt an unwanted amber. Calcite contamination in filter-grade quartz grit blocks the pores and cripples a water treatment plant's throughput. A talc-cut mica fails a cosmetics heavy-metals test weeks before a product launch.

These are not hypothetical scenarios. They represent the most common and costly failures in industrial mineral procurement. The root cause is almost always the same: the supplier was not properly qualified before the first order was placed.

This guide sets out the seven tests and documents that should be standard in any mineral supplier qualification process — regardless of whether you are sourcing quartz, feldspar, dolomite, mica, or any other industrial mineral. Completing this checklist before committing to a supply relationship is not bureaucratic overhead; it is basic protection for your production process and your customers.

Why Unqualified Mineral Supply Is a Production Risk

Industrial minerals are functional raw materials. Unlike commodity chemicals with standardised purity guaranteed by regulatory frameworks, industrial minerals are geological products whose chemistry varies by deposit, mining face, and processing run. A "quartz powder" from one supplier may be 99.7% SiO₂ with Fe₂O₃ below 0.03%. The same product description from another supplier may hide 0.2% Fe₂O₃ — enough to introduce significant colour shift in a borosilicate glass melt or to discolour a white ceramic tile body.

Two real-world failure modes are worth illustrating:

The following seven tests and documents are designed to surface these risks before they reach your production line.

1

XRF Chemical Analysis — Certificate of Analysis (CoA)

X-ray fluorescence (XRF) analysis is the industry standard for verifying the elemental oxide composition of industrial minerals. A properly issued CoA derived from XRF should contain batch-specific results — not specification ranges — for the following parameters at minimum:

Red flag: A CoA that shows only specification ranges (e.g., "SiO₂ >99%") rather than actual batch results is not a Certificate of Analysis — it is a restatement of the product data sheet. Every legitimate batch-level CoA should carry a unique batch or lot number, a sample date, and a laboratory or instrument reference. If your supplier cannot produce batch-specific results, the mineral has not been tested on the outgoing lot.

Always request that the CoA reference the specific shipment, container, or lot number corresponding to your purchase order. For high-value or sensitive applications, request that the analysis be performed by an accredited third-party laboratory (SGS, Bureau Veritas, Intertek) rather than relying solely on the supplier's in-house results.

2

Particle Size Distribution (PSD)

A mineral described as "200 mesh" tells you only that the bulk of material passes a 75-micron sieve. It tells you nothing about the proportion of fines below 10 microns, the coarse fraction sitting just under the sieve cut, or the D50 (median particle size) of the actual distribution. For most industrial applications, this information is critical.

The correct method for characterising industrial mineral PSD is laser diffraction (e.g., using a Malvern Mastersizer or equivalent instrument). This provides a full particle size distribution curve and the key statistical values:

These three values characterise the spread of the distribution. A narrow gap between D10 and D90 indicates a tightly controlled, uniform grind. A wide gap indicates a broad, inconsistent distribution that may cause issues in ceramic body formulation, paint viscosity, or filter bed performance.

Red flag: A PSD declaration consisting solely of a sieve designation ("200 mesh" or "325 mesh") with no laser diffraction data is insufficient for process-critical applications. Sieve analysis cannot characterise sub-45-micron fractions accurately, and the coarse tail of a distribution — which sieve analysis also misses — is often the source of surface defects in ceramics or graininess in paint films.

What to ask for: a full PSD report in PDF format showing the distribution curve and the D10/D50/D90 values, along with the measurement method and instrument reference. This should be available on a per-batch basis, not just as a product master specification.

3

Whiteness Index

For minerals used in ceramics, paint, coatings, cosmetics, and paper, whiteness is a functional specification — not an aesthetic preference. It directly determines the optical performance of the end product and the loading rate required to achieve target opacity or brightness.

Whiteness is measured using a calibrated spectrophotometer and reported as either:

Reference benchmarks for quality industrial minerals:

Red flag: Whiteness described only as "white" or "high brightness" without a numerical value and measurement method is unverifiable. Demand a numeric whiteness reading with the instrument type and calibration standard referenced on the test report.
4

Moisture Content

Moisture in industrial minerals affects three things: processing efficiency, shelf life, and weight-based pricing accuracy. A mineral purchased at 10 mt may contain 0.8% free moisture — meaning you are paying for 80 kg of water per container that contributes nothing to your process and may cause caking, handling problems, or equipment corrosion.

Acceptable moisture limits for common minerals:

Red flag: Moisture reported only on the product master specification sheet — not on the batch CoA — means the outgoing lot was not tested. Free moisture varies by season, storage conditions, and processing run. It must be tested on the specific outgoing shipment, not the product archetype.
5

Acid Solubility

Acid solubility measures the proportion of a mineral that dissolves when exposed to hydrochloric acid under standardised conditions. It is a proxy for carbonate content — calcite and dolomite dissolve readily; true silica (SiO₂) does not. This test is critical for two applications in particular: quartz grit for water treatment filtration and feldspar for ceramics.

For quartz grit used in rapid sand and multimedia water treatment filters, acid solubility must be below limits specified in:

The acceptance criterion under these standards is typically <0.5% acid-soluble content. A quartz grit with even 1–2% calcite contamination will fail this test and is unsuitable for drinking water contact applications. In the field, excess acid-soluble material dissolves during backwash cycles and deposits calcium carbonate scale, progressively clogging the filter bed.

Red flag: Filter-grade quartz grit with no acid solubility test result on the CoA is a disqualifying omission. This test is straightforward and inexpensive — any legitimate filter-grade mineral supplier conducts it routinely on every production lot.
6

Mine and Processing Plant Audit

Chemistry tests verify product quality at the moment of sampling. They do not verify the origin of the mineral, the sustainability of the supply chain, or the operational reality of the producer's facility. A mine audit addresses the structural, not the analytical, risk in your supply chain.

What to ask for when auditing a mineral supplier's source:

Red flag: A supplier who cannot or will not disclose the name or location of their mine or source producer is almost certainly a trader (middleman) who has no direct relationship with or control over quality at the extraction stage. This is not inherently disqualifying — trading houses exist for good reason — but it means quality control is removed from the chain, and the buyer must compensate with more rigorous product testing.
7

Heavy Metals Report and REACH Declaration

For any mineral intended for cosmetics, personal care, food contact, or consumer product applications, heavy metals testing is mandatory — not optional. This is particularly critical for mica, which is used in cosmetics, pearlescent pigments, and personal care formulations.

The required heavy metals thresholds for cosmetic-grade minerals (per EU Cosmetics Regulation 1223/2009, which Australian cosmetics manufacturers commonly reference):

For supply into European markets or to manufacturers with REACH compliance requirements:

Red flag: Mica supplied without a heavy metals report is a serious compliance risk in cosmetics and personal care. Some Indian mica deposits, particularly artisanally mined material, carry elevated lead and arsenic levels that would fail regulatory limits. Never assume compliance — test every new supply source.

What PIME Provides as Standard

At Pacific Industrial Mineral Enterprises, supplier qualification is embedded in our supply chain — not something buyers need to negotiate. For every product and every shipment, we provide:

Note for Australian buyers: PIME operates under Australian company law (ABN 17 697 333 378) and issues documentation that meets Australian import compliance requirements. All products are accompanied by a commercial invoice, packing list, bill of lading, phytosanitary certificate where applicable, and Certificate of Origin — streamlining customs clearance at Australian ports.

The qualification process does not need to be adversarial. A reputable supplier welcomes these questions because they demonstrate that the buyer understands the product and values quality. A supplier who resists providing standard qualification documents is signalling, loudly, that you should look elsewhere.