In short. Thirty-three terms in six groups: product and particle size, materials, chemistry and quality, processing, silicon, and export. Each definition links to a full page with sources.
Product and particle size
Quartz grits
Crushed and screened quartz in particle-size fractions, also called crushed quartz, quartz granules or, in coarser sizes, quartz chips. See Quartz grits.
Quartz sand
Quartz in sand sizes. Crushed quartz grits sold as quartz sand are classed under HS 2506.10; natural silica and quartz sands under HS 2505.10. See Quartz, quartzite and silica sand.
Quartz powder
Quartz milled to a fine mesh or micron grade. Used as a filler, it is often called silica flour. See Quartz powder.
Silica flour
Finely ground quartz used as a filler in coatings, polymers, sealants and flooring. Also called quartz flour, ground quartz or ground silica; the finest grades are sold as micronised quartz. See Quartz powder as a filler.
Mesh
The number of openings per linear inch of a test sieve. A higher mesh number means a finer sieve. See Mesh to micron.
Micron (µm)
One thousandth of a millimetre. Powder sizes are usually given in microns. See Mesh to micron.
Particle-size distribution (PSD)
How much of a sample falls in each size range, measured by sieving or laser diffraction. See Mesh to micron.
D50
The median particle size: half of the sample is finer than this size. See Mesh to micron.
AFS grain fineness number
A single number for the average fineness of a foundry sand, worked out from a sieve analysis. Higher numbers mean finer sand. See Quartz for foundry sand.
Effective size and uniformity coefficient
Filter sand measures. Effective size is the sieve opening that passes 10% of the sand by weight (d10). The uniformity coefficient is d60 divided by d10. See Quartz filter sand.
Materials
Quartz
The mineral silicon dioxide, SiO2. See Quartz, quartzite and silica sand.
Vein quartz
Quartz formed when hydrothermal fluid rising from within the earth solidifies, as veins in the host rock. Our quartz is Sri Lankan vein quartz. See Sri Lanka’s vein quartz.
Quartzite
A rock made mostly of quartz grains, formed from sandstone. See Quartz, quartzite and silica sand.
Silica sand
Natural sand made mostly of quartz grains. HS subheading 2505.10. See Quartz, quartzite and silica sand.
Silica
Silicon dioxide, SiO2. Quartz is one of its mineral forms. See Quartz, quartzite and silica sand.
Engineered stone
Manufactured slabs, often sold as “quartz”, made mostly of crushed quartz bound with resin. See Quartz for engineered stone.
Silica ramming mass
A dry refractory lining for induction furnaces, rammed in place from graded quartz. See Quartz for refractories.
Chemistry and quality
Certificate of Analysis (COA)
A batch-specific test report. Ours reports SiO2, Fe2O3, Al2O3, TiO2, CaO, Na2O, K2O, moisture and particle-size distribution. See Certificate of Analysis and test methods.
Fe2O3 (iron oxide)
Iron reported as oxide. Iron colours glass and ceramics, so most buyers set an upper limit. See Quartz for glass manufacturing.
3N, 4N and 5N
Shorthand for SiO2 content by the count of nines: 3N means three nines. The figure is usually calculated by difference from the impurities measured. See Quartz purity grades.
High-purity quartz (HPQ)
Natural quartz with less than 100 parts per million of total impurities, as the U.S. Geological Survey defines it. See Quartz purity grades.
Lattice impurities
Elements such as aluminium, lithium, boron, sodium and titanium held within the quartz crystal structure. Leaching does little to them. See How quartz is purified.
Fluid inclusion
A micron-size pocket of liquid or gas trapped inside a quartz grain. See How quartz is purified.
Crystalline silica
Silica in crystalline form, such as quartz (CAS 14808-60-7). Its fine dust, respirable crystalline silica, is a workplace health hazard, so powder is handled with dust control. See FAQ.
Processing
Dry processing
Processing without water: crushing, milling, screening and dry separation. Our process is dry and physical. See How we process quartz.
Magnetic separation
Removing iron-bearing minerals from a quartz stream with magnets. See How quartz is purified.
Calcination
Heating quartz to drive off volatile matter and open up inclusions before leaching. See How quartz is purified.
Silicon
Silicon
The element Si, made from quartz or quartzite reduced with carbon in submerged arc furnaces. See Quartz for silicon.
Ferrosilicon
An alloy of iron and silicon made from quartz or quartzite. The standard grades are 50% and 75% silicon. See Quartz for silicon.
Export
HS 2506.10
The Harmonized System subheading for quartz other than natural sands. Sri Lanka splits it into raw vein quartz (2506.10.10) and value-added vein quartz (2506.10.90). See Exporting quartz from Sri Lanka.
FOB (Free On Board)
An Incoterms® 2020 rule for sea transport. The seller delivers the goods on board the vessel nominated by the buyer at the named port of shipment, where risk passes to the buyer. See Exporting quartz from Sri Lanka.
CIF (Cost, Insurance and Freight)
An Incoterms® 2020 rule for sea transport. The seller pays freight and minimum insurance to the named destination port; risk passes when the goods are on board at the port of shipment. See Exporting quartz from Sri Lanka.
Bulk bag (FIBC)
A flexible intermediate bulk container: a large woven bag for dry bulk material. We ship grits and powder in bulk bags. See Exporting quartz from Sri Lanka.
Sources
- World Customs Organization, Harmonized System 2022, heading 25.06 (quartz; quartzite) and Chapter 25 notes
- World Customs Organization, Harmonized System 2022, heading 25.05 (natural sands)
- U.S. Geological Survey, Mineral Commodity Summaries 2026: Quartz (high-purity and industrial cultured crystal)
- U.S. Geological Survey, Mineral Commodity Summaries 2026: Silicon
- Lin, M., Pei, Z. and Lei, S. (2017), “Mineralogy and Processing of Hydrothermal Vein Quartz from Hengche, Hubei Province (China)”, Minerals 7(9), 161
- International Chamber of Commerce, Incoterms® 2020
Definitions are summaries. The linked pages give the detail and the sources. Our product values are on each batch COA. Published October 2026.
