Use ground calcium carbonate when the process was qualified on a milled limestone, marble or chalk filler. Use precipitated calcium carbonate when it was qualified on a particle that was grown in a reactor, with a shape and a surface the mill cannot copy by grinding harder. If you do not know which of those you have, do not let a trader decide from the price. Send the current data sheet. NAGTAR will not offer PCC when the qualified Algerian path is GCC, and it will not relabel GCC to fill a PCC enquiry. The product page is calcium carbonate. Grade, mesh and the failures that follow a wrong industry fit are covered in calcium carbonate from Algeria.
What buyers mean by GCC and PCC
GCC means ground calcium carbonate. Someone mined a carbonate rock, crushed it, and milled it to a size. The crystal in the bag is a fragment of the crystal that was in the ground. PCC means precipitated calcium carbonate. Someone made the particles in a chemical process, usually by reacting a lime slurry with carbon dioxide under controlled conditions, sometimes by another precipitation route. The shape is a result of that process, not of the quarry face.
Buyers blur the names. "Calcite", "natural carbonate", "synthetic carbonate", "coating carbonate" and "filler carbonate" all show up on enquiries. Natural, in this trade, usually points at GCC. Synthetic or precipitated points at PCC. Coating carbonate often means a fine, bright grade for paper or paint, and it might be either family depending on the mill. Filler carbonate is usually GCC, until a plant has written PCC into the formula.
The desk treats the family as a contractual fact. A goods description that says only "calcium carbonate" is incomplete if the plant will reject the wrong family. Say GCC or PCC in the first line when you know it. If you do not, say "unknown, data sheet attached" rather than guessing from a mesh.
NAGTAR does not operate a carbonate plant and does not publish a production route for Algerian supply. The description below is how the two families are made in the industry, so a buyer can see why they are not substitutes. What can be offered is whatever qualified path exists for the brief. When that path is grinding, the offer says GCC.
The decision: ground or precipitated
The decision is which particle your process already believes in.
Start from the line, not from the origin. A PVC pipe compound, a polypropylene masterbatch, a joint compound and a lot of architectural paint were built on GCC. A paper coating, some breathable films, some sealants and some high-brightness coatings were built on a PCC shape. Changing family because a ground lot is easier to find is a formulation change. It belongs in the lab, on a trial quantity, with the formulator's sign-off. It does not belong in a substitution clause on a shipment.
Ask four questions before you compare offers:
- Does the current specification name the family, or only a mesh and a brightness?
- Is the particle shape, surface area or oil absorption on the data sheet something the plant has limits for?
- Has this plant ever run the other family in this formula, with a written result?
- If the answer to the third question is no, is this enquiry a trial or a cargo?
If it is a cargo, buy the family the plant already runs. If it is a trial, book it as a trial, in a quantity the plant can keep separate, and do not scale the purchase order until the trial is signed.
Cost sits behind that decision, not in front of it. GCC is a quarrying and grinding cost: rock, power, classification, sometimes a surface treatment, then packing. PCC is a chemical-plant cost: energy to calcine and slake, or another reagent route, then control of concentration, temperature and time so the particles grow into one shape, then filtration and drying. Buyers should expect precipitated material to cost more per tonne than a ground filler of ordinary fineness, because the plant behind it does more work. That gap is the reason to use PCC only where shape, surface or brightness does a job that a finer GCC has already failed to do. It is not a reason to call a ground lot precipitated. There is no public NAGTAR price for either family. The comparison is logical, and the number comes later, on a qualified lot.
A finer grind is the usual attempt to avoid that gap. It sometimes fixes a residue problem. It does not turn fragments of rock into scalenohedral or cubic particles grown in a reactor. If the formula needs that shape, a 2 micron GCC is still GCC.
Specifications desks ask for
Both families can be written with the same headings. The headings do not make them the same product. Send methods, and say which family the method was developed on.
Family. GCC or PCC, stated. If the PCC must be a named crystal habit, say so: scalenohedral, rhombohedral, prismatic, cubic, or acicular. Those words are the specification. "Precipitated, any shape" is only acceptable when the plant has truly no shape limit. Many plants that think they have no shape limit discover one when oil absorption or gloss moves.
Particle size. GCC from a classifier has a distribution the mill and the separator produced. It can be broad or tight. A coarse tail is the usual complaint. PCC can be grown to a narrower distribution, which is why coaters and some film lines prefer it, but a PCC lot can still carry agglomerates from drying. Ask for d50, a top cut or a sieve residue, and the method. Do not convert a PCC d50 into a mesh and assume a GCC mill can hit it. Mesh language is how GCC is often sold. It is a poor description of a precipitated coating grade.
Shape and surface. For GCC, buyers rarely specify shape beyond "ground calcite", because the mill breaks what the deposit gave it. They specify size and a coating, often stearate, when the resin needs the surface changed. For PCC, surface area and oil absorption are often the real controls, because the grown shape creates them. If your lab has an oil-absorption limit or a BET habit, put it in the brief. If it does not test them, do not copy them from a competitor's brochure.
Brightness. PCC is often brighter than GCC from the same district, because precipitation can leave some of the rock's colour behind and because fine, controlled particles scatter light differently. GCC brightness is mostly the deposit: a white marble grinds brighter than a grey limestone, and no classifier fixes iron that is inside the crystal. State the method, as on the grade and mesh note. Do not send a single "whiteness percent" with no method and expect either family to be judged by it.
Moisture and coating. PCC is dried out of a wet process, so residual moisture and the way it was dried affect flow. GCC can be dry-ground or wet-ground and dried. A stearate or other treatment is an extra specification on top of the family. An uncoated PCC does not replace a coated GCC in a polyolefin just because both are carbonate.
NAGTAR confirms figures on the lot it can qualify. It does not publish a standing brightness, a standing surface area, or a standing purity for GCC or for PCC.
Uses and the wrong carbonate
Plastics. Most commodity filling, pipe, cable, profiles and a lot of masterbatch is GCC. The compounder wants a known size, a moisture limit, and sometimes a coating. PCC shows up where the particle has a job beyond filling: a particular impact behaviour, a breathable film that needs a shape which will debond from the polymer in a controlled way, or a surface the GCC trial already failed. Dropping PCC into a pipe compound that was balanced on GCC usually buys a higher-surface filler the formula did not ask for. Dropping GCC into a film line that was set up on a PCC habit usually shows as pinholes, the wrong porosity, or a gloss the customer rejects. Say which of those plants you are.
Paint. Extender use is often GCC: a sized, bright enough ground carbonate with an oil absorption the formula can live with. PCC appears in some coatings for sheen control, for a tighter size, or for brightness the local GCC does not reach. A ground grade that is too coarse flashes. A precipitated grade with a hungry surface can break the binder demand. Match the family the formula was written on. "Paint grade" is not a family.
Paper. Filler in the sheet is a common GCC job. Coating on the sheet is a common PCC job in the wider industry, because coaters care about gloss, opacity and a scratch-free blade. Some coating uses very fine GCC. If you are a mill, say filler or coating, and say which family the coater or the wet end runs today. A filler GCC offered into a coater is the wrong carbonate even when the assay is excellent. NAGTAR will not dress a ground lot up as a coating PCC.
Adhesives, sealants and compounds. Both families appear. Sealant formulas are sensitive to surface area and moisture. Send the family name from the current raw-material code, not a generic "filler carbonate".
Regulated uses. Food, pharmaceutical and some personal-care grades are a different buying problem from industrial filler. If that is the brief, say it in the first sentence so it is not handled as a plastics or paint lot. Do not assume an industrial GCC or PCC path covers a regulated specification.
The wrong carbonate fails quietly at first. The certificate of analysis can pass a purity line both families share. The complaint arrives as dispersion, gloss, porosity, viscosity or abrasion. That is why the family belongs in the contract, not only in the technical chat.
Packing and the cargo
Family changes the cargo, not just the data sheet.
GCC at filler fineness often moves in big bags or in bulk, in a lined container or a clean hold, because the volumes are larger and the powder is a standard industrial filler. Bulk GCC still needs a clean previous cargo. Cement, clinker, coal or a coloured mineral in the hold shows up as specks. Rain on an open hatch cakes the surface and puts lumps into the receiver's screen. Grab discharge of a fine ground grade in wind is a loss and a dust problem. Pneumatic discharge needs a powder that flows and a silo that can take the rate.
PCC is more often a bagged, identity-controlled cargo. The particles are finer or more fragile as agglomerates, the surface area is higher, and a bulk stow mixed with another white powder cannot be argued back into a shape specification. Lined big bags, with the lot kept separate, are the default conversation. Bulk PCC is a special plan: it needs a receiver who has run that powder in bulk before, a hold or a box that will not contaminate it, and a moisture story the drying step can survive. Do not propose bulk PCC only because the GCC business on the same route is bulk.
Coated grades, GCC or PCC, pick up a second packing rule. The treatment is on the surface. Abrasion in a long pneumatic line, water through a torn liner, and heat in a closed container can change how that surface behaves even when the carbonate assay does not move. If the coating is contractual, the packing has to protect it. Say so.
Do not complete a GCC quantity with PCC bags, or the reverse, to fill a booking. They are different lines, different samples, different claims. A stevedore who builds one stack has mixed the shipment. Mark the family on the bags and on the packing list in the same words the contract uses.
Discharge at the plant should keep the family separate from the other carbonate already in the silo. A silo heel of GCC under a PCC delivery is a blend the formulator did not approve. If the plant has only one white-powder silo, bagged delivery and a dedicated hopper are the safer first cargo.
Documents, inspection and Incoterms
The papers have to name the family or they do not describe the goods.
Invoice, packing list and bill of lading should say ground calcium carbonate or precipitated calcium carbonate, plus the grade name or the size treatment you agreed, plus the packing. "Calcium carbonate, industrial" is how a letter of credit gets presented and how a claim gets argued into nothing. If the credit can carry the words GCC or PCC, put them there. If the bank's goods line is short, put the family on the certificate of analysis and make that certificate a required document.
The certificate of analysis is a lot document. For GCC it should cover the tests the ground grade can support: size by the agreed method, moisture, and brightness or chemistry if those are contractual. For PCC it should cover the tests that define the precipitated grade, which may include shape description, surface or oil absorption, and size, as agreed. A GCC lab sheet attached to a PCC contract is the wrong piece of paper, even when every printed number looks tidy. A brochure is not a certificate.
Certificate of origin supports customs. It does not prove the family. A safety data sheet is for the warehouse file. Inspection, when you want it, should sample the lot that will load, record the packing, and test the contractual list. Agree whose result governs. For a first PCC cargo into a plant that has only run GCC, a pre-shipment sample through the real process is the test that matters. A quay survey will not see film porosity.
Incoterms do not repair a family error. FOB means you take the vessel and risk passes on board, so the loading sample and the analysis have to be closed in the way the contract says. CFR means freight is arranged for you and risk still passes at loading. CIF adds a defined insurance cover, often too narrow if you needed wet-damage protection on hygroscopic bags. Name the discharge port up front. The loading place follows the qualified lot. A PCC trial in containers should not inherit the bulk FOB wording of a GCC parcel.
If the qualified path cannot sign the family you wrote, the document set will not be invented to match. The offer changes, or it stops.
How Algerian supply is qualified
NAGTAR qualifies a path. It does not invent a precipitation plant to answer a PCC enquiry, and it does not describe a grinding line as if the desk ran it.
The practical sequence is short. You name GCC or PCC, or you attach the sheet of the powder you run now. The desk asks what an Algerian source can actually supply with documents. If the source is a ground carbonate that meets the GCC brief, that is the offer. If the brief says PCC and the path in hand is GCC, the answer is that PCC is not available on that path. You can then decide to trial GCC, in writing, as a different product, or you can stop. You will not receive GCC under a PCC description.
Qualification of a GCC lot covers the size tests, moisture, any coating, packing, and brightness or chemistry when you asked for them and the source can measure them. Qualification of a PCC lot would cover the precipitated specification the plant needs, including shape if shape is the reason you asked for PCC. A sample before a first industrial stem is part of qualification when the application is new to the origin. A capacity claim is not. Availability is the window the path can commit.
Read the industry failures on the Algeria grade note if the open question is mesh and use, and you already know the family is ground. Stay on this page if the open question is which family to write into the contract.
What to send in the inquiry
Send English, one page, to the trade inquiry or from the calcium carbonate page.
- GCC or PCC, or "unknown" with the current data sheet attached.
- The process: pipe, film, masterbatch, paint, paper filler, paper coating, sealant, or another named line.
- Any shape, surface, oil-absorption, size, brightness, moisture or coating limit you actually enforce, with the method.
- Whether a trial of the other family is allowed, or forbidden.
- Packing you can discharge without mixing silos, quantity, destination and window.
If the sheet in your hand does not say ground or precipitated, ask your plant before you ask for a price. The desk can tell you what a qualified Algerian path is. It cannot reconstruct your formula from a mesh.
Will you offer PCC if the Algerian path is GCC?
No. The offer follows the path that can be qualified. When that path is ground calcium carbonate, the contract says GCC. A buyer who needs precipitated material is told that this path does not cover it. There is no renaming, and no "equivalent" line that hides the family.
Does a finer GCC count as PCC?
No. Extra grinding can tighten a top cut and raise brightness a little by removing a coarse fraction. It does not grow a new crystal habit. If your reject history is shape, surface area or a film behaviour tied to precipitated particles, a finer ground lot is a different trial, not a quiet replacement.
Which plants usually stay with GCC?
Pipe, cable, many profiles, a lot of masterbatch, joint compounds, and paper filler are usually GCC conversations. Paint extenders often are too. "Usually" is the market habit, not your formula. If your code says PCC, the habit of the neighbouring plant is irrelevant.
Which plants usually ask for PCC?
Paper coating, some breathable films, and formulas that have already failed on GCC brightness or shape. Some sealants and some coatings sit here as well. Say the habit your line uses. A coating enquiry that is actually a filler enquiry should be corrected before anyone looks for a precipitated lot.
What if our data sheet never names the family?
Then the enquiry is not ready for a cargo. Ask the plant for the raw-material code and the supplier's description of the powder they run today. Look for "ground", "natural", "precipitated" or "synthetic", and for a shape word. If those words are missing, send the sheet anyway and mark the enquiry as identification, not as a shipment. A price at that stage would be a price for an assumption.
Can we decide from brightness alone?
No. Brightness is one reading, method-dependent, and both families can be bright or dull depending on the lot. A bright GCC is still ground. A dull PCC is still precipitated. Use brightness as a limit inside the family you already need. Use the family itself as the first line of the specification.