why are sands and clay soft?

Answer 1

We are dealing with an illusion caused by grain size and moisture content here. In fact sand is quite hard because it is made up of individual rock and mineral grains. Limestone and quartz are pretty hard materials. If a sand is damp, or has very small rounded grains, it can feel soft to the hand however.

Clays on the other hand are soft because they are created by the chemical weathering of other minerals (such as pyroxene or feldspar) and the individual clay units are microscopic in size. Clays usually contain a high proportion of water in their structure as well (it can be as high as 70%).

When a geologist in the field can't make out the whether a rock is a siltstone (clastic) or clay (chemical) because the grain sizes are too small to see, a simple test is to break off a small fragment put it between ones teeth. If its chewy and soft, its a clay. If its hard and gritty, its a silt.
(Warning - experts only folks. Some rocks contain poisonous minerals so don't go around randomly tasting rocks.)

Answer 2

Sand can't actually be 'soft', as silicates are hard, no matter how small the particle. (Unless you melt them, eg molten glass, but that's not what you had in mind). The particles -- grains -- of sand can be very eroded, and smooth, and tiny, which creates the feeling of 'soft sand'. Beaches that get bashed up by hard waves crashing on them constantly, and don't get a lot of 'new' sand, from the ocean-bottom, deposited on them regularly, are the 'softest'. Obviously, the most eroded, smallest sand particulates occur in deserts, where the wind causes the sand particles to erode against each other. You've never seen sand as fine and 'soft' as there is in North Africa, or places like Syria. The sand-storms there are lethal. But the particles are tiny and round.

Clays are another story. The 'softness' of clays depends on moisture content, and density. Most clay is not very dense, and so remains quite absorbent, and so long as it stays in its natural state, is 'soft'. Dry clays out, and they're usually hard, brittle, and crumbly. The process of firing moulded clay heats it so fast that the water evaporates, to be replaced with air pockets, so the formed clay retains its original volume. Allowed to dry out over time, the clay loses volume, as moisture is a significant part of the volume of any clay.

This is only elaboration on above answers, most of which were excellent.

Answer 3

sand and clay is soft because the molecules or particles are spread out more than most solids. In most solids the molecules are very close together which is the same as saying that the molecules are dense/densly packed together. this density causes the substance to be quite hard. with sand the tiny grains have air between them and the combination of air and grains of sand creates a quite soft substance. with clay the molecules are simply spread out and the space between the molecules again causes the softness of the substance

Answer 4

but are they.

IS cooked clay soft?

The question is not such a good one because what you see in a rock is thousands of particles that have been formed by cooling magma. These crystals are hard and feel hard to touch because it is a solid lump. A single grain of sand is also very hard, its just so small that you do not feel it. The same happens with clay. Sand is broken down bedrock. Clay is generally the result of pressure deposits and glacial silts that have generally been further compressed and hence form clays. But clay particles are in their tiny fragments also quite strong, just the lack of bonding between the particles makes them feel softer.

Answer 5

Because the molecular bonds are broken. A sand crystal is really a small version of a much larger rock. The crystal itself is quite hard as the bonds within the crystal are still there. A handful of sand is soft because their are no molecular bonds between the grains as they have been broken down by the wind, rain, sea over thousands of years.

Answer 6

clays and silts are described as hard and soft. Usually sands are described as loose or dense. Clays may be soft because they are not compacted very much or don't have any consolidation or cementing.

Answer 7

because of d gradual disintegration of rocks and d parent material and bederock of d soil dats why its soft

Answer 8

Because of their water content.