Alpha-Quartz
Alpha-Quartz is trigonal single-crystal SiO2 — naturally birefringent and piezoelectric, unlike amorphous fused silica — available as synthetic optical (SYN-OPT), natural (NAT) and swept (SYN-Q-SWEPT) material and as X-cut and Z-cut plates.
Reference datasheet — Alpha-Quartz is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SYN-OPT condition
Alpha-Quartz tempers and conditions
Alpha-Quartz is supplied in 5 conditions, soft to hard. SYN-OPT is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Natural quartz crystal | Pick when a natural-origin or very large single-domain blank is required; yield is low because of inclusions, twinning and veils. | 48 | 0 | 1,120 HV | 8 W/m·K | |
X-CUT / Y-CUT | Standard cut for waveplates and Wollaston/Rochon polarizers, where the optic axis lies in the plate plane. | 50 | 0 | 1,120 HV | 6 W/m·K | |
SYN-OPTDefault Cultured (hydrothermal) optical-grade single crystal | Default choice for waveplates, polarizing prisms and UV–NIR windows: inclusion-free, striae-free cultured crystal with reproducible birefringence. | 55 | 0 | 1,150 HV | 8 W/m·K | |
electronic-grade swept cultured quartz (premium Q, low Al/alkali) | Use for precision oscillators, filters and radiation-hard resonators where infrared Q and low alkali-ion content control aging. | 55 | 0 | 1,150 HV | 8 W/m·K | |
Plate normal parallel to optic (c) axis | Choose when light must travel along the optic axis (no birefringence) or for optical-rotation and etch-pit work. | 60 | 0 | 1,180 HV | 11 W/m·K |
What is Alpha-Quartz?
Alpha-Quartz is trigonal single-crystal SiO2 — naturally birefringent and piezoelectric, unlike amorphous fused silica — available as synthetic optical (SYN-OPT), natural (NAT) and swept (SYN-Q-SWEPT) material and as X-cut and Z-cut plates. It is used for waveplates and retarders, polarizing prisms, UV optics and precision piezoelectric resonators, with an elastic modulus of 87 GPa. The crystal is brittle with rhombohedral cleavage and rates only 6 for machinability, and service stops at 500 °C because the α→β inversion at 573 °C twins the crystal. Fused silica is the choice when birefringence is unwanted. Alpha-Quartz has a density of 2.65 g/cm³ (0.0957 lb/in³), lighter than 52% of glass grades. It melts at 1,710°C (3,110 °F). Alpha-Quartz has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. Elongation at break is 0% and the elastic modulus is 87 GPa (12.6 Msi).
What is Alpha-Quartz used for?
- waveplates/retarders
- polarizing prisms
- piezoelectric resonators
- UV optics
Advantages
- Good corrosion resistance — 92/100, better than 81% of glass grades
- Conducts heat well — 8 W/m·K (4.62 BTU/hr·ft·°F), better than 76% of glass grades
Limitations
- Difficult to machine — 6/100, worse than 87% of glass grades
- High embodied carbon — 18 kg CO₂/kg, worse than 76% of glass grades
Alpha-Quartz properties
Typical room-temperature values for Alpha-Quartz-SYN-OPT; bars are the position among glass grades.
Physical5
Alpha-Quartz has a density of 2.65 g/cm³ (0.0957 lb/in³), lighter than 52% of glass grades. It melts at 1,710°C (3,110 °F).
Mechanical13
Alpha-Quartz has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. Elongation at break is 0% and the elastic modulus is 87 GPa (12.6 Msi).
Thermal5
Alpha-Quartz is rated for continuous service to 500°C (932 °F). It conducts heat at 8 W/m·K (4.62 BTU/hr·ft·°F), better than 76% of glass grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical5
Alpha-Quartz is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (92/100), better than 81% of glass grades.
Sustainability4
Producing a kilogram of Alpha-Quartz takes about 250 MJ of energy and emits 18 kg of CO₂ — more than 76% of glass grades. Typical recycled content is 0%.
Manufacturability2
Alpha-Quartz's machinability is not recommended (6/100, worse than 87% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. Alpha-Quartz is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Alpha-Quartz
Is Alpha-Quartz easy to machine?
Diamond only — ID/wire sawing, core drilling and lapping with loose SiC/diamond abrasive; brittle with rhombohedral cleavage, so keep light loads and flood coolant, and orient cuts to the crystallographic axes within arc-minutes.
Can Alpha-Quartz be welded?
Not weldable or fusible without destroying the crystal; join by optical contacting, UV-cure or epoxy cementing, or by metallized/solder mounting for resonators.
Can Alpha-Quartz be formed, bent or molded?
No hot forming — the material is grown hydrothermally to near-net boules and heating past 573 °C causes the α→β inversion and twinning; all shaping is subtractive.
Alpha-Quartz chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Alsubstitutional Al–alkali centres control Q and radiation sensitivity | ≤ 0 | 5×10⁻⁴ |
| Naremoved by electrodiffusion (sweeping) | ≤ 0 | 2×10⁻⁴ |
| Li | ≤ 0 | 2×10⁻⁴ |
| Fecolouring impurity | ≤ 5×10⁻⁴ | 1×10⁻⁴ |
| OHstructural water; measured as IR alpha-3500 Q value | ≤ 0.01 | 0 |
| SiO2crystalline alpha polymorph; Si 46.7 wt%, O 53.3 wt% | ≥ 99.99 (balance) |
What surface finishes work on Alpha-Quartz?
Pitch or CeO2 polishing gives λ/10 flats and <1 nm Ra; ammonium-bifluoride or HF etch removes subsurface damage and reveals twins; AR or metal electrode coatings are applied by sputtering/evaporation.
How much does Alpha-Quartz cost?
Alpha-Quartz is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Alpha-Quartz — frequently asked
What is Alpha-Quartz used for?
Alpha-Quartz is typically used for waveplates/retarders, polarizing prisms, piezoelectric resonators and UV optics. In short: birefringent piezoelectric SiO2; axis-oriented optical cuts; 573 °C inversion limit.
What is the tensile strength of Alpha-Quartz?
Alpha-Quartz has a typical tensile strength of 55 MPa (7.98 ksi) — stronger than 71% of glass grades. Strength varies by condition: see the 5 listed tempers.
Is Alpha-Quartz easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 87% of glass grades). Diamond only — ID/wire sawing, core drilling and lapping with loose SiC/diamond abrasive; brittle with rhombohedral cleavage, so keep light loads and flood coolant, and orient cuts to the crystallographic axes within arc-minutes.
Can Alpha-Quartz be welded?
Not weldable or fusible without destroying the crystal; join by optical contacting, UV-cure or epoxy cementing, or by metallized/solder mounting for resonators.
What surface finishes work on Alpha-Quartz?
Pitch or CeO2 polishing gives λ/10 flats and <1 nm Ra; ammonium-bifluoride or HF etch removes subsurface damage and reveals twins; AR or metal electrode coatings are applied by sputtering/evaporation.
Can Alpha-Quartz be formed, bent or molded?
No hot forming — the material is grown hydrothermally to near-net boules and heating past 573 °C causes the α→β inversion and twinning; all shaping is subtractive.
What is the maximum service temperature of Alpha-Quartz?
Alpha-Quartz is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Alpha-Quartz cost?
Alpha-Quartz is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- IEC 60758 — Synthetic quartz crystal: specifications and guide to use — IEC (2016)
- Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- Handbook of Optical Constants of Solids — Academic Press (1998)
- Crystal Quartz (SiO2) optical material datasheet — Crystran / Hilger Crystals (2023)
- Landolt-Börnstein: Elastic, piezoelectric and dielectric constants of quartz — Springer (1979)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.