Direct answer: what is the difference between GCC and PCC?
To prepare this report, the Minerallum team compared a 2026 experimental study of commercial GCC and PCC, several reviews on precipitated calcium carbonate synthesis, and applied studies in paper, PVC and sealants.
The fundamental difference is the manufacturing route.
- GCC - Ground Calcium Carbonate: natural calcium carbonate that is extracted, prepared, ground and classified.
- PCC - Precipitated Calcium Carbonate: calcium carbonate recreated through controlled chemical precipitation.
Both products can consist predominantly of CaCO₃ and can even contain the same mineral phase, such as calcite.
Yet they do not necessarily behave in the same way.
Manufacturing influences:
- particle morphology;
- particle-size distribution;
- porosity;
- specific surface area;
- bulk density;
- surface chemistry;
- agglomeration;
- purity and impurity profile;
- dispersion inside a formulation.
A recent experimental comparison by Ersoy et al. illustrates this clearly. For the two specific commercial grades studied, the GCC consisted mainly of angular, irregular and blocky solid masses, whereas the PCC appeared as porous aggregates built from roughly 50–100 nm cubic-rhombohedral primary crystallites. The PCC in that study had substantially higher surface area and lower bulk density [1].
Those dimensions and morphologies describe the two samples investigated, not every GCC and PCC on the market.
The useful distinction is therefore not “PCC = fine and premium, GCC = coarse and economical.” Real grades must be compared through measured properties.
| Criterion | GCC | PCC |
|---|---|---|
| Origin | Natural mineral material | Controlled precipitation |
| Structure-forming step | Grinding + classification | Nucleation + crystal growth |
| Morphology | Inherited from mineral and modified by grinding | Tunable through precipitation conditions |
| Particle size | Controlled by grinding/classification | Controlled by crystallisation + separation |
| Polymorph | Linked to prepared mineral feed | Can be influenced by process conditions |
| Surface | Depends on fineness, grinding and treatment | Strongly affected by size, morphology and porosity |
| Industrial choice | Based on the actual grade | Based on the actual grade |
How is GCC produced?
GCC retains a direct connection with the natural mineral feed.
An industrial route may include:
- extraction or receipt of limestone, marble or another calcite-rich material;
- crushing;
- washing or sorting where required;
- grinding;
- micronising;
- particle-size classification;
- wet grinding or additional steps for selected fine grades;
- drying where required;
- surface treatment for selected applications;
- packaging.
Final chemistry therefore depends first on the deposit.
Natural carbonate can contain, depending on origin:
- magnesium;
- silica;
- aluminosilicates;
- iron;
- other trace elements.
Mineral processing can reduce selected undesirable fractions, but GCC fundamentally remains a natural solid that is mechanically reduced and separated.
This explains why two GCC products with the same D50 can differ in:
- brightness;
- effective hardness;
- coarse residue;
- secondary mineralogy;
- particle shape;
- surface properties;
- abrasivity;
- lot-to-lot consistency.
The 2026 Ersoy et al. study likewise shows why morphology, surface area and bulk density should be considered together rather than inferred from median particle size alone [1].
How is PCC produced?
Conventional PCC production from carbonate feed adds a chemical transformation.
A common route contains three main stages.
1. Calcination
Calcium carbonate is heated to form quicklime:
CaCO₃ → CaO + CO₂
2. Hydration
Quicklime reacts with water:
CaO + H₂O → Ca(OH)₂
3. Carbonation
Carbon dioxide is introduced into hydrated-lime slurry:
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
Erdogan and Eken describe this route based on carbonate calcination, formation of Ca(OH)₂ in water and subsequent precipitation by reaction with CO₂ [2].
Erdogan and Eken also investigated a calcination–dissolution–precipitation route using waste marble powder. Their product consisted mainly of micrometre-scale rhombohedral calcium carbonate crystals and reached a D50 of 1.682 µm under the optimised conditions of that study [2].
That number is not a “standard PCC particle size.” It demonstrates that final particle size is a result of the process.
Teir, Eloneva and Zevenhoven describe the conventional route based on mined carbonate while investigating alternative calcium-silicate routes for PCC production [3].
Why precipitation provides greater morphological control
Grinding GCC fractures and reduces crystals that already exist.
PCC production creates new crystals.
That is the central structural difference.
Precipitation involves two major phenomena:
- nucleation;
- crystal growth.
Reviews by Liendo et al. and Boyjoo, Pareek and Liu show that multiple process variables can change particle size, crystalline phase and morphology [4–5].
These include:
- temperature;
- pH;
- calcium concentration;
- CO₂ concentration or flow;
- agitation;
- mixing rate;
- reaction time;
- pressure;
- foreign ions;
- additive type and concentration.
PCC can therefore be engineered with very different morphologies.
Calcite, aragonite and vaterite: PCC is not one structure
CaCO₃ has several crystalline polymorphs.
The three forms most frequently discussed in precipitation research are:
- calcite;
- aragonite;
- vaterite.
Calcite is the thermodynamically stable phase under common ambient conditions, while other phases may form depending on processing conditions.
Liendo et al. show that carbonation conditions strongly affect crystalline phase, morphology and size [4].
Boyjoo et al. likewise relate particle formation to variables including temperature, pH, ionic ratio, solvent, mixing and additives [5].
It is therefore inaccurate to define PCC merely as:
“very fine synthetic CaCO₃.”
A specification may also need to identify:
- polymorph;
- crystal habit;
- porosity;
- specific surface area;
- particle-size distribution.
Particle size: why GCC versus PCC is not a D50 comparison
A common mistake is to compare:
- a GCC with D50 = X;
- a PCC with D50 = Y;
and then attribute all performance differences to D50.
That is incomplete.
Particle-size distribution should be described with several points:
- D10;
- D50;
- D90;
- D97 or D98;
- coarse residue;
- ultrafine fraction.
But even a complete PSD does not directly describe:
- specific surface area;
- internal porosity;
- agglomerates;
- roughness;
- shape.
The 2026 comparison is especially useful here: the GCC investigated could be finer by selected particle-size indicators while the PCC still showed higher specific surface area because of its porous morphology and aggregate structure [1].
Finer by particle-size measurement does not automatically mean higher specific surface area.
Specific surface area: why it matters so much in formulation
Specific surface area describes the total surface available per unit mass.
As that surface increases, more interface must be wetted or treated.
Depending on the formulation, this can alter:
- dispersant demand;
- binder demand;
- viscosity;
- wetting;
- additive adsorption;
- surface-treatment requirement;
- agglomeration tendency.
This is one reason why price per tonne alone can mislead.
A cheaper grade that requires substantially more dispersant, binder or processing adjustment can lose part of its apparent economic advantage.
Conversely, high surface area is not automatically desirable. In some formulations it makes dispersion more difficult.
True density and bulk density are different properties
Crystal density and powder bulk density answer different questions.
True density concerns the solid material itself.
Bulk density includes particle packing and the voids between particles.
A powder made from porous aggregates can therefore occupy more volume at the same mass.
Ersoy et al. illustrate this: the more porous PCC in their comparison had lower bulk density than the GCC [1].
This matters for:
- volumetric dosing;
- storage;
- bag filling;
- pneumatic conveying;
- hopper capacity;
- powder flow.
Purity: precipitation can purify, but the PCC label does not guarantee it
One potential advantage of PCC production is that chemical transformation can separate part of the impurities in the original material.
The 2024 work of Jembere, Genet and Sintayehu provides a clear example.
Starting from a lime feed containing several impurities, their dissolution and precipitation route produced PCC containing 99.2% CaCO₃ [8].
This demonstrates that precipitation can produce highly purified calcium carbonate in a particular process.
It does not justify saying:
“Every PCC is purer than every GCC.”
A naturally high-purity calcite deposit can also produce GCC with very high CaCO₃ content.
For purchasing, compare actual measurements:
- CaCO₃;
- MgO or MgCO₃;
- SiO₂;
- Fe₂O₃;
- Al₂O₃;
- insolubles;
- relevant trace elements.
Morphology and porosity have direct application consequences
Shape differences are not merely visible under a microscope.
They can change the structure of a composite or coating.
In paper, for example, particle packing influences:
- porosity;
- light scattering;
- ink absorption;
- smoothness;
- gloss;
- water movement during coating.
Barhoum et al. prepared nanoscale precipitated CaCO₃ particles and compared them with commercial GCC in paper coating. The precipitated particles in their study were calcite, rhombohedral and below 100 nm average diameter [6].
Coating performance also changed with the surface treatment applied to these particles.
The lesson is not that PCC “wins” against GCC.
It is that size + morphology + surface + modification operate as a system.
Paper and paperboard: GCC and PCC can serve different objectives
A 2025 study by Kim, Yoo, Lee and Seo compared four coarse GCC grades of different sizes and a porous PCC in paperboard precoating formulations [7].
The researchers found that:
- GCC particle size changed coating-colour viscosity and dewatering;
- the PCC investigated contained relatively small and highly porous particles;
- pigment blends produced different coating behaviours.
This shows why a paper formulation cannot be decided only by asking:
“GCC or PCC?”
The actual target must be defined:
- coating rheology;
- dewatering;
- coating porosity;
- brightness;
- gloss;
- printability;
- pigment cost;
- machine speed.
Plastics and PVC: performance depends on grade and formulation
In plastics, calcium carbonate can influence:
- stiffness;
- impact behaviour;
- density;
- dimensional stability;
- processing;
- cost;
- appearance.
GCC/PCC selection still cannot be separated from:
- particle size;
- surface chemistry;
- treatment;
- loading;
- polymer;
- other additives.
In the PVC study by Jembere et al., the researchers produced predominantly calcitic PCC and blended it with a commercial filler [8].
In their experimental formulation, filler blends containing 25%, 50% and 75% PCC satisfied the mechanical criteria examined, while complete replacement slightly reduced selected properties [8].
That experiment does not establish a universal GCC/PCC ratio.
It demonstrates the opposite:
Changing calcium-carbonate family should be evaluated at several substitution levels in the actual formulation.
Our report on calcium carbonate in PVC examines particle size, coating and dispersion in that application in more detail.
Sealants and adhesives: dispersion can dominate the decision
Highly filled systems such as sealants and adhesives make the influence of these variables particularly visible:
- surface area;
- wetting;
- agglomeration;
- viscosity;
- loading.
In 2025, Zhang et al. studied different filler types and loadings in a bio-based polyurethane engineered sealant [9].
In their specific formulation, the PCC investigated gave the best dispersion among the fillers tested and the clearest reinforcing effect. They recommended 10 wt% PCC for their system, while excessive PCC reduced dispersion uniformity and could decrease strength [9].
That result should never become:
“Use 10% PCC in every sealant.”
It supports a more general qualification rule:
Filler benefit depends on a loading and dispersion window specific to each formulation.
Can PCC be called “better” than GCC?
No.
PCC provides an additional degree of control during synthesis.
GCC provides a more direct connection to a natural deposit and a mechanical processing chain.
Depending on the application, requirements may favour:
GCC
- availability at high volumes;
- broad particle-size ranges;
- naturally high-purity grades;
- competitive total cost;
- need for a relatively dense powder;
- an existing formulation already optimised around GCC.
PCC
- specific morphology;
- defined surface or porosity;
- precipitation-controlled particle distribution;
- control of crystalline form;
- functionality linked to a particular structure;
- purity achieved through chemical transformation.
None of these are absolute.
Ultrafine GCC exists.
PCC can be micrometre-sized.
GCC can be extremely pure.
PCC can be agglomerated.
The decision must therefore be based on grade data, not the acronym.
How to compare GCC and PCC correctly
We recommend five blocks.
1. Chemistry and mineralogy
Request:
- CaCO₃;
- MgO/MgCO₃;
- SiO₂;
- Fe₂O₃;
- Al₂O₃;
- loss on ignition;
- calcite/aragonite/vaterite phase where relevant.
2. Particle-size distribution
Compare:
- D10;
- D50;
- D90;
- D97/D98;
- sieve residue;
- complete distribution;
- measurement method.
3. Morphology and surface
Examine:
- SEM;
- particle shape;
- agglomeration;
- BET;
- porosity;
- bulk density;
- wetting.
4. Surface treatment
Check:
- treated or untreated;
- treatment chemistry;
- treatment level;
- hydrophobicity;
- free unbound fraction;
- treatment consistency.
5. Application testing
Measure properties that matter to the real product.
| Application | Possible controls |
|---|---|
| PVC / plastics | torque, pressure, dispersion, impact, stiffness, Vicat, appearance |
| Paper / coating | viscosity, water retention, porosity, gloss, opacity, printability |
| Paints | viscosity, filling, gloss, matting, stability, oil absorption |
| Sealants / adhesives | rheology, extrusion, slump, modulus, adhesion, cure |
| Rubber | dispersion, hardness, modulus, tensile, elongation, dynamic behaviour |
Compare formulation cost rather than price per tonne
A useful commercial comparison includes:
real cost = delivered price + loading + additives + losses + process impact + reject rate
A more expensive PCC can justify its cost in an application where its structure creates a valuable performance gain.
A cheaper GCC can remain the better choice when:
- required properties are already achieved;
- loading is high;
- annual volume is large;
- the formulation is robust;
- special morphology adds no useful benefit.
The reverse can also occur.
For this reason, substitutions should be assessed as cost per unit of conforming product, not simply cost per tonne of filler.
Quality control should reflect the production route
For GCC, consistency depends strongly on:
- deposit variability;
- mining selectivity;
- mineral preparation;
- grinding;
- classification;
- surface treatment.
For PCC, consistency depends strongly on:
- reactant purity;
- calcination or calcium source;
- hydration;
- temperature;
- pH;
- CO₂ transfer;
- agitation;
- nucleation/growth kinetics;
- separation;
- drying;
- final treatment.
The Liendo et al. review shows how many carbonation parameters can influence crystalline phase, morphology and particle size [4].
Supplier qualification should therefore identify critical controls appropriate to each production route.
Practical case: same D50, different choice
Imagine two grades with very similar D50.
Grade A - GCC
- compact particles;
- moderate specific surface area;
- higher bulk density;
- distribution controlled by classification.
Grade B - PCC
- porous aggregates;
- greater specific surface area;
- lower bulk density;
- morphology created through precipitation.
Even if D50 is similar, grade B may require:
- more liquid to wet the available surface;
- more dispersant;
- a different mixing regime;
- adjusted volumetric dosing.
Grade A may in turn have:
- a different top cut;
- different particle shape;
- different mechanical response.
The test result therefore depends on the application.
This is exactly what the recent GCC/PCC comparison illustrates: morphology can become the variable that explains several of the other measured differences [1].
Relationship with micronized calcium carbonate
“Micronized” and “precipitated” are not synonyms.
A GCC can be micronized through grinding and classification.
A PCC can be micrometre- or nanometre-sized depending on the process.
Micronized mainly describes a fineness scale or size-reduction/classification route; it does not define GCC versus PCC origin.
For more detail, see our report on micronized calcium carbonate.
An eight-step selection method
Step 1 - Define the filler function
Cost, stiffness, opacity, porosity, rheology, impact, surface?
Step 2 - Describe the current grade
Do not stop at “GCC.”
Record its measured properties.
Step 3 - Define acceptable deviations
Which properties can change without compromising the product?
Step 4 - Compare the powders
Chemistry, PSD, BET, density, morphology and surface.
Step 5 - Compare at identical loading
Start with a constant formulation.
Step 6 - Measure processing
Record machine variables.
Step 7 - Measure the finished product
Compare against the control.
Step 8 - Optimise
Once compatibility is demonstrated, adjust filler loading and additives.
This method avoids attributing to GCC or PCC changes that were actually caused by several formulation variables moving at the same time.
Conclusion: GCC and PCC are two routes to CaCO₃, not two quality levels
Our review leads to four conclusions.
1. Manufacturing route is the fundamental difference
GCC is prepared from natural carbonate through mechanical processing.
PCC is recreated through chemical precipitation [2–5].
2. Manufacturing route changes powder structure
Morphology, porosity, surface area, bulk density and agglomeration can differ substantially [1,4–5].
3. The acronym does not predict performance
Research in paper, PVC and sealants shows that results depend on the specific grade and the specific formulation [6–9].
4. Selection should begin with measured properties
The right question is not:
“GCC or PCC: which is better?”
It is:
“Which grade provides the combination of chemistry, particle size, morphology, surface and consistency required by our process and finished product?”
That question turns a comparison of two white powders into a genuine industrial qualification.