Clay is usually found near water features, surface stone is the easiest to gather, and sand and gravel come from river bars and pits. Test every source before committing the site to it, because a clay that cracks, a stone that crumbles or a sand full of salt and silt ruins whatever is built from it.
Locating and checking local deposits of clay, building stone, sand and gravel for bricks, mortar, plaster, foundations and drainage.
Each Material Has a Use and a Test
The carrier lists the uses: clay for bricks, mortar, plaster and pottery, usually found near water features; stone, where surface stone is easiest and quarrying requires significant labor and tools; sand and gravel for foundations, mortar and drainage layers.
| Material | Used for | How to check |
|---|---|---|
| Clay | Bricks, plaster, mortar, pottery | Jar and ribbon tests; see below |
| Stone | Foundations, walls | Hard, dense, not flaking; see Stone Types |
| Sand | Mortar, cob, plaster | Clean, gritty, free of silt and salt |
| Gravel | Foundations, drainage | Clean, hard, graded |
What You Need
- A shovel and a jar — for sampling and settling tests.
- A hammer — for stone.
- Fresh water — for washing sand.
Method: Find, Sample, Test
Step 1: Clay Look in river banks, pond edges and below the topsoil in cuttings. See Finding Clay for specific locations. Test with the ribbon and jar tests in Soil Composition Testing and the firing tests in Clay Testing.
Step 2: Stone Gather surface stone first. Hit a sample hard: a stone that splits in layers, powders or crumbles under the hammer is poor. Hard stone that rings and breaks cleanly is better. Soak a piece for a day: stone that falls apart in water is unsuitable for damp locations.
Step 3: Sand Rub a damp pinch between your fingers: clean sand feels gritty, silty sand stains the skin and feels smooth. Fill a jar a third full, shake with water and let it settle: a thick silt or clay layer above the sand layer means the sand needs washing. Taste a rinse of beach or river-mouth sand: if it tastes salty, it carries salt that draws moisture into walls and weakens mortar.
Step 4: Quantity and distance Estimate how much you need and how far it must travel. See Resource Proximity.
Worked Example
A wall 10 m long, 2.5 m high and 0.5 m thick has a volume of 10 x 2.5 x 0.5 = 12.5 m3. At an assumed average of 2 tonnes per cubic metre of built stone wall (a planning figure, not a measured one), that is 12.5 x 2 = 25 tonnes of material for a single wall, which shows why the stone source must be close.
Common Mistakes
- Using a stone that looks hard but is layered — it splits when frozen or wet.
- Using beach sand untreated — salt stays in the wall.
- Digging out the bank that protects your water — do not undercut river banks or spring areas.
Safety
Quarrying and crushing stone creates dust that scars lungs
Dust from cutting, crushing or dressing stone that contains quartz can cause the incurable lung disease silicosis over years of exposure. Work upwind, wet the stone when cutting, and cover mouth and nose. Quarry faces also fall: never work beneath an overhang or an unsupported face.
What’s Next
- Learn next: Clay Testing — whether the clay will fire and bind
- Combine with: Stone Foundation — putting the stone to work