The journey of quartz from a raw mineral to a high-performance industrial material begins with precise quartz stone grinding and a deep understanding of its fundamental characteristics. This article provides a detailed overview of quartz material classification, its key physical and chemical properties, and its diverse industrial applications, highlighting why this material is indispensable in modern technology.
Quartz materials can be classified based on their crystalline state, purity, and intended use. The common classification systems are as follows:
1. By Crystalline State:
• Crystalline Quartz: Natural quartz crystals with a regular geometric shape, commonly found in quartz sand and quartzite.
• Non-Crystalline Quartz (Fused Silica/Quartz Glass): Produced by high-temperature fusion of quartz ore, it lacks a long-range crystal structure, resulting in high homogeneity and stability.
2. By Purity:
• High-Purity Quartz: Purity >99.99%, suitable for optical, electronic, and scientific research applications.
• Metallurgical Grade Quartz: Purity around 90%, primarily used in metallurgy and construction.
• Standard Quartz: Purity below 90%, widely used in everyday products.
3. By Application:
• Optical Quartz: High-purity quartz for manufacturing lenses, prisms, and optical fibers.
• Piezoelectric Quartz: Quartz with a piezoelectric effect, used for sensors and oscillators.
• Electronic Quartz: High-purity quartz for electronic devices and insulating materials.
Key Physical Parameters of Quartz Materials
The physical parameters of quartz directly influence its performance and applications. Here are some critical parameters:
| Parameter | Crystalline Quartz | Quartz Glass (Fused Silica) |
| Density (ρ) | ~2.65 g/cm³ | ~2.2 g/cm³ |
| Thermal Expansion Coefficient (α) | ~0.28 x 10⁻⁶/K (RT) | ~0.55 x 10⁻⁶/K (RT) |
| Refractive Index (η) | – | 1.46 (Visible Light) |
| Resistivity (ρ) | – | ≥1.0 x 10¹⁴ Ω·cm |
In summary, the unique properties of quartz give it broad application prospects in technology and industry. Deepening our understanding of these characteristics and continuously refining purification processes will further expand its application range, driving new material development.
1 Physicochemical Properties of Natural vs. Synthetic Quartz
Quartz is a common chemical mineral prized for its excellent physicochemical stability, leading to widespread use in electronics, optics, and construction. Based on origin, it is primarily classified as natural or synthetic, which share similarities but also exhibit key differences.
1. Physical Properties:
• Crystal Structure: Both natural and synthetic quartz are primarily α-SiO₂ (low-temperature quartz) with a trigonal crystal system. At high temperatures (>870°C), it reversibly transforms to β-SiO₂ (high-temperature quartz) with a hexagonal structure.
• Optical Properties: Quartz offers excellent optical properties, including high transmittance, low absorption coefficient, and nonlinear effects. Its transmission range spans from UV to infrared (~220 nm to ~2450 nm).
• Mechanical Properties: High hardness (Mohs 7), high elastic modulus, and good compressive strength, making it resistant to stress and wear.
• Thermal Properties: Excellent thermal stability and one of the lowest thermal expansion coefficients among oxides (~5.5×10⁻⁷/K between 20-200°C), ensuring dimensional stability at high temperatures.
2. Chemical Properties:
Both types exhibit high chemical stability due to strong Si-O bonds. However, they can be etched by strong agents like hydrofluoric acid (HF), following the reaction:
SiO₂ + 4HF → SiF₄ + 2H₂O
Synthetic quartz, due to its higher purity, generally offers superior chemical stability.
3. Fused Silica (Quartz Glass)
This non-crystalline form, made by melting and rapidly cooling quartz, has distinct properties:
• Higher Transmittance: Due to the absence of light-scattering grain boundaries.
• Lower Mechanical Strength: Lacks the reinforcing crystal structure.
• Higher Thermal Conductivity: No grain boundaries to impede heat flow.
Despite these differences, it retains high stability, low thermal expansion, and a high melting point.
Synthetic quartz is preferred for high-purity applications like lasers and optical sensors, while fused silica is ideal for high-temperature, high-vacuum, and corrosive environments.
2 Crystal Forms and Structure Analysis of Quartz Materials
The lattice symmetry and anisotropy of quartz are crucial for understanding its mechanical, optical, and electrical properties.
• α-Quartz (Common Quartz): The most common form. Space group P3₁21. Features a continuous network of [SiO₄] tetrahedra connected via corner-sharing, forming a hexagonal crystal structure.
• β-Quartz: Exists at high temperatures. Space group C2/m (monoclinic). Its structure is more disordered compared to α-quartz.
• γ-Quartz: A rare trigonal polymorph (space group P3) with a more complex lattice structure involving three tetrahedral units. It is more common in synthetic environments.
Advanced techniques like HRTEM, XRD, and SEM are used to analyze lattice periods, defects, and microcracks, providing the theoretical basis for designing new quartz-based materials with tailored properties.
3 Industrial Classification and Application Scenarios
Industrially, quartz is classified based on chemical composition, impurity content, and physical properties, which directly influence its application and value.
1. Industrial Classification:
The primary division is between Natural Quartz (e.g., silica, flint, amethyst) and Synthetic Quartz. Synthetic quartz is further divided into:
| Category | Main Component | Impurity Content (%) | Impurity Particle Size (μm) | Key Characteristics |
| Silica/Quartzite | SiO₂ | < 1 | 0.1 – 100 | Good light transmittance, high chemical stability, low thermal expansion coefficient |
| Flint | SiO₂ | 1 – 5 | Varied | High mechanical strength, but poor light transmittance |
| Amethyst | SiO₂ | Trace | Varied | Exhibits piezoelectric & semiconductor properties; high optical damage sensitivity |
| Quartz Glass (Fused Silica) | SiO₂ (≥ 99.99%) | Very Low | 1 – 10,000 | High transmittance, high purity, low thermal expansion, high temperature & corrosion resistance |
| Doped Quartz Glass | SiO₂ + Dopant Elements | Very Low | 1 – 10,000 | Functional diversity, e.g., coloration, IR filtering, laser medium |
• Quartz Glass (Fused Silica): Known for high purity and excellent physicochemical properties.
• Synthetic Crystalline Quartz: Valued for its piezoelectric and pyroelectric effects.
2. Application Scenarios:
(1) Quartz Glass (Fused Silica)
• Telecommunications: The primary material for optical fiber preforms, enabling low-loss, high-bandwidth data transmission.
• Optics: Used for lenses, prisms, windows, and filters in instruments like telescopes, microscopes, and lasers due to its high transmittance across a broad spectrum.
• Electronics: Serves as a key material for components in electron tubes, insulators, and crystal oscillator bases due to its excellent thermal stability and electrical insulation.
• Consumer Goods: Found in baking oven windows, high-temperature reaction kettles, and medical sterilization equipment.
(2) Crystalline Quartz
• Electronics: The piezoelectric effect is harnessed to create essential components like crystal oscillators and resonators, providing precise timing in phones, computers, and communication devices.
• Sensing: The pyroelectric effect is utilized in thermal and infrared sensors for temperature measurement and control systems.
• Energy: Used in piezoelectric ceramics for energy harvesting applications (converting mechanical energy to electrical energy).
The industrial classification of quartz is intrinsically linked to its application scenarios. As technology advances, the demand for higher-performance quartz materials will continue to drive innovation in purification processes and new material development.
Equipments by Epic Powder for Quartz Grinding
Calcium carbonate Ball Mill and Classifier Production Line
International standard processing line, used with classifier, can produce products with multiple particle size at the same time.
Features:
The product particle size control is flexible, special design is adopted to reduce noise and emission; Automatic control, easy to operate, According to the scale of investment, it provides personalized customized scheme and provides value-added services.
Application:
Calcium carbonate (calcite, marble, lime stone, chalk), quartz, zircon, paillite, barite, kaoline, dolomite, magnesite, alumina, super fine cement, slag, steel slag.
Horizontal Air Classifier
Features:
High speed, accurate vertex cutting; clean production process; program control system, easy to adjust and operate.
- Application:
Widely used in mineral industry (especially suitable for classification of non mineral products such as calcium carbonate, kaolin, quartz, talc, mica), metallurgy, abrasives, ceramics, refractory, medicine, pesticide, food, health care products, new materials, etc..
Epic Powder
The path from raw quartz to advanced industrial materials demands precision at every stage, especially in the critical quartz stone grinding and classification processes. Epic Powder provides grinding and sizing solutions engineered to handle the extreme hardness of quartz, ensuring high purity, precise particle size distribution, and optimal throughput for your specific application. Maximize your product’s performance and value by partnering with Epic Powder – where advanced milling technology meets proven expertise in mineral processing. Let us help you optimize your quartz material production; contact our experts for a customized solution today.
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— Posted by Jason Wang, Senior Engineer