Quartz or kwarts
Quartz is one of the best-known and most common minerals on Earth. With a hardness of about 7 on the Mohs scale, quartz is often interesting for the rock tumbler, but not every piece of quartz polishes equally easily.
Quartz is often called quartz internationally. The mineral consists of silicon dioxide and occurs in many rocks, sand, gravel and crystal forms. For polishing stones, the combination of hardness, compactness and susceptibility to fracture is especially important.
What is quartz?
Quartz is a mineral made up of silicon and oxygen. It is one of the most common minerals in the Earth’s crust and occurs in all kinds of geological environments. You can find quartz in granite, sandstone, quartz veins, river gravel and metamorphic rocks, among others.
Quartz usually has a hardness of around 7 on the Mohs scale. That makes it a relatively hard stone. As a result, quartz is more resistant to wear than softer minerals such as calcite or fluorite. At the same time, quartz can sometimes have fracture lines, milky areas or sharp crystal points that affect the result in a rock tumbler or rock polisher.
Hardness
Quartz has a hardness of around 7. In principle, that makes it suitable for tumbling, especially when the pieces are compact and not too cracked.
Appearance
Quartz can be clear, white, grey, smoky, pink, purple or yellowish. The colour depends on inclusions, trace elements and the specific variety.
Is quartz suitable for a rock tumbler?
Yes, quartz can be suitable for a rock tumbler. Compact pieces of quartz in particular, rose quartz, smoky quartz, aventurine and amethyst can be interesting to tumble. However, quartz is not always as predictable as agate or jasper. Some pieces have internal fractures or splintery zones, which can cause damage during tumbling.
- Choose compact pieces: avoid quartz with many deep cracks or loose crystal points.
- Mix with similar hardness: preferably combine quartz with stones of roughly the same hardness.
- Allow enough time: quartz is hard and often needs several weeks.
- Clean between stages: leftover coarse grit can create new scratches later on.
- Use polishing powder: for real shine, fine grit alone is usually not enough.
Practical tip: if you want to tumble quartz or other suitable stones, also take a look at the category rough stones for rock tumblers.
Polishing quartz in 5 steps
Polishing quartz with a rock tumbler usually takes place in several stages. A useful starting point is four grit stages followed by one polishing stage. The grit stages make the stone progressively smoother. The polishing stage then creates the shine.
Coarse grit
For rounding off sharp edges and reducing rough forms. This stage determines much of the final shape.
Medium grit
For reducing scratches from the coarse stage and evening out the surface.
Fine grit
For further refinement. Quartz will feel smoother by then, but it usually will not yet have a full shine.
Very fine grit or pre-polish
For preparation for the final polish. This stage helps to reduce small scratches further.
Polishing powder
For shine. Only use polishing powder once the quartz has already become nicely smooth in the previous stages.
Please note: quartz with many fracture lines or sharp crystal points may behave differently during tumbling than rounded, compact pieces.
Overview: quartz and the polishing tumbler
| Property | What does this mean? | For the rock tumbler |
|---|---|---|
| Hardness around 7 | Quartz is relatively hard. | Well suited, but the process takes time. |
| Many varieties | Quartz occurs as rock crystal, rose quartz, smoky quartz, amethyst and more. | Each variety may react differently to tumbling. |
| Fracture lines | Some pieces have internal cracks or splintery zones. | These pieces may be damaged or remain dull. |
| Compact structure | Dense, solid pieces are usually more promising. | Often gives a better final result than crumbly pieces. |
Different types of quartz
Quartz is an umbrella term for several well-known varieties. Some varieties are sold as separate stones, while mineralogically they belong to the quartz family. For the rock tumbler, what matters most is how hard, compact and fracture-free the piece is.
Rock crystal
Clear to colourless quartz. Beautiful crystals are often better kept as collector’s pieces than simply tumbled.
Rose quartz
Pink variety of quartz that is regularly tumbled. Compact pieces can develop a lovely soft sheen.
Amethyst
Purple variety of quartz. Suitable in compact pieces, but crystal points or druzy edges can be fragile.
Citrine and smoky quartz
Yellow to brown varieties of quartz. Here too, compact pieces are more suitable than brittle crystal pieces.
Polish quartz or other stones?
For a good result, you need suitable stones, a rock tumbler, grit, polishing powder and enough patience. Quartz can turn out beautifully, but preferably choose compact pieces without deep fractures.
Common mistakes when polishing quartz
Quartz is hard enough for a rock tumbler, but that does not mean every piece will automatically turn out beautifully. Fracture lines, sharp crystals and changing grit too quickly can all affect the final result.
- Using pieces that are too rough: crystal points and splinters can break off more easily.
- Moving through the coarse stage too quickly: scratches and sharp edges will then remain visible.
- Leaving coarse grit behind: that can create scratches again in later stages.
- Too little fill: stones can hit each other too hard and get damaged.
- Mixing the wrong stones: large differences in hardness give inconsistent results.
- Skipping the polishing stage: without polishing powder, quartz often remains less shiny.
Can you find quartz in the Netherlands?
Yes, quartz can be found in the Netherlands. It occurs, among other places, in sand, gravel, glacial erratics and river deposits. Especially in gravel-rich areas, along rivers, on some beaches and in imported gravel you can find quartz-like stones.
Not every piece of quartz you find is suitable for the rock tumbler. Pay attention to compactness, fracture lines and crumbly edges. If you want to read more about searching for stones yourself, also see the page which stones can you find in the Netherlands and Belgium.
Buy quartz or collect it yourself?
Collecting quartz yourself is fun and educational, but the result is less predictable. Bought rough stones are often more convenient when you want to make a batch straight away that is better suited to a rock tumbler.
Collect quartz yourself
Fun as part of the hobby. Just make sure to watch out for cracks, crystal points and crumbly pieces.
Buy rough quartz or mixed stones
Practical if you want to start with material that is better suited to tumbling. For that, see the category rough stones.
Frequently asked questions about quartz
Is quartz suitable for a rock tumbler?
Yes, quartz can be suitable for a rock tumbler. Preferably choose compact pieces without many deep cracks or crumbly crystal edges.
How hard is quartz?
Quartz has a hardness of about 7 on the Mohs scale. That makes it clearly harder than, for example, fluorite or calcite.
How long does it take to polish quartz?
Polishing quartz usually takes several weeks. Because quartz is hard, the first stage with coarse grit in particular needs enough time.
Can you find quartz in the Netherlands?
Yes, quartz occurs in the Netherlands in sand, gravel, river deposits and glacial erratics. Not every piece you find is suitable for the polishing tumbler.
What is the difference between kwarts and quartz?
Kwarts is the Dutch name and quartz is the English name. In webshops and international information, both terms are often used for the same mineral.