Below is a list of the key chemical parameters and elements to analyze in the quartz grits, as well as the ideal and our thresholds or considerations to ensure long-term quality of Artificial quartz stone slabs
1. Silicon Dioxide (SiO₂) Content
Ideal Range: ≥ 98% pure SiO₂.
Aero’s Range: 99.87% pure SiO₂.
Reason: Quartz grits should be primarily composed of silicon dioxide (SiO₂), which is a highly stable and inert compound. The higher the SiO₂ content, the less likely the quartz will react with resins or degrade over time. Anything less than 98% SiO₂ might suggest the presence of impurities that could lead to discoloration or chemical instability.
Analysis Method: X-ray fluorescence (XRF) or gravimetric analysis.
2. Iron Content (Fe)
Ideal Range: < 0.05% Fe.
Aero’s Range: 0.002%
Reason: Iron is a major cause of yellowing in quartz slabs, as it can oxidize and cause rust-like discoloration. Even small amounts of iron can lead to problems over time. Iron is typically found in the form of iron oxide (Fe₂O₃) or ferrous compounds, which can react with resins, especially under UV exposure.
Analysis Method: XRF or atomic absorption spectroscopy (AAS).
3. Aluminum Oxide (Al₂O₃) Content
Ideal Range: < 2% Al₂O₃.
Aero’s Range: 0.008%
Reason: Aluminum in excess can interfere with the bonding of resin to quartz, and it can also contribute to staining or color instability over time. While aluminum is relatively inert, when present in high amounts, it may affect the durability and appearance of the final product.
Analysis Method: XRF or inductively coupled plasma mass spectrometry (ICP-MS).
4. Calcium Oxide (CaO) Content
Ideal Range: < 1% CaO.
Aero’s Range: 0.016%
Reason: Calcium (usually in the form of calcium carbonate or calcium oxides) can be found in quartz grits. When reacting with resin or exposed to environmental elements like moisture, it could cause the formation of stains or yellowish discoloration over time.
Analysis Method: XRF or ICP-MS.
5. Magnesium Oxide (MgO) Content
Ideal Range: < 1% MgO.
Aero’s Range: 0.007%
Reason: Like calcium, magnesium compounds in quartz can react with resins or other substances, leading to yellowing or discoloration. Magnesium oxides can also cause a slight shift in color when exposed to certain environmental factors.
Analysis Method: XRF or ICP-MS.
6. Iron Minerals (Hematite, Magnetite, Goethite)
Ideal Range: Negligible (< 0.1%).
Aero’s Range: Nill
Reason: Any iron-bearing minerals such as hematite, magnetite, or goethite can lead to noticeable rust-like discolorations if they are present in large amounts. These minerals can react with UV light and moisture, resulting in the oxidation of iron and causing yellowish discoloration over time.
Analysis Method: XRD (X-ray diffraction) to identify specific mineral phases.
7. Sulfur Content (S)
Ideal Range: < 0.1% S.
Aero’s Range: Nill
Reason: Sulfur in quartz grits, often in the form of sulfides (like pyrite), can cause yellowing when it interacts with resin or other materials. Pyrite (fool’s gold), when exposed to air, can oxidize to form sulfuric acid, contributing to discoloration or degradation.
Analysis Method: XRF or ICP-MS.
8. Organic Compounds and Impurities
Ideal Range: < 0.1% organic content.
Aero’s Range: 0.08%
Reason: Organic matter can interact with the resin and cause chemical reactions that result in yellowing. Organic impurities may come from the mining process or environmental exposure. High organic content should be avoided as it may lead to poor bonding or chemical instability.
Analysis Method: Loss on Ignition (LOI) at high temperature to quantify organic impurities.
9. Titanium Dioxide (TiO₂) Content
Ideal Range: < 0.5% TiO₂.
Aero’s Range: 0.0006%
Reason: Titanium dioxide can cause color instability in some cases, and if present in excessive amounts, it can shift the color of the quartz towards a yellowish hue. However, in controlled amounts, TiO₂ can also serve as a stabilizer and improve resistance to UV degradation.
Analysis Method: XRF or ICP-MS.
10. Heavy Metals (Lead, Arsenic, Mercury)
Ideal Range: < 0.01% heavy metals (Lead, Arsenic, Mercury).
Aero’s Range: Nill
Reason: Heavy metals, like lead, arsenic, and mercury, are toxic and can also cause long-term discoloration. Their presence, even in trace amounts, could cause chemical instability or undesirable reactions, leading to yellowing or environmental hazards.
Analysis Method: ICP-MS or atomic absorption spectroscopy (AAS).
11. Particle Size Distribution
Ideal Range: Consistent and uniform particle size.
Aero’s Range: Excellent Consistency and uniform particle size
Reason: Size distribution impacts the evenness of resin bonding and curing. A well-graded quartz grit with a controlled particle size helps achieve a more uniform final product with fewer areas that might be prone to discoloration.
Analysis Method: Laser diffraction or sieving analysis.
Additional Considerations:
X-ray Diffraction (XRD): Useful for identifying mineral phases (such as any iron-bearing minerals, feldspar, or clay minerals) that could contribute to discoloration.
UV-VIS Spectroscopy: Can be used to assess UV stability of the quartz grits, as the absorption of UV light can be a good indicator of their potential for yellowing when exposed to UV rays.
Thermal Analysis: Techniques like Thermogravimetric Analysis (TGA) can be used to measure the thermal stability of the quartz, ensuring it doesn’t break down under normal production conditions.
When it comes to producing high-quality engineered quartz surfaces, the purity, chemistry and grading of quartz grits make all the difference.
At Aero, we are proud to offer Quartz grits with industry-leading specifications that help our partners deliver exceptional and long-lasting Quartz surfaces — free from discoloration, yellowing or structural degradation.
For more details, please feel free to contact us or visit www.aeromintech.com
