Sand

**Composition and Definition:**
– Sand grains are smaller than gravel and coarser than silt.
– Sand contains silica (silicon dioxide) as the most common constituent.
– Sand may also be composed of calcium carbonate or calcium sulfate.
– Sand is a non-renewable resource over human timescales.
– Desert sand is not suitable for making concrete.
– Unified Soil Classification System defines sand as particles with a diameter between 0.074 and 4.75 millimeters.
– Geologists classify sand particles with diameters ranging from 0.0625mm to 2mm.
– Sand falls between gravel and silt in terms of particle size.
– Sand can be categorized as fine, medium, and coarse based on size.
– Sand feels gritty when rubbed between fingers, unlike silt which feels like flour.

**Mineral Composition and Sources:**
– Silica (SiO2) in the form of quartz is the most common mineral in sand.
– Sand composition varies based on local rock sources and conditions.
– Bright white sands in tropical areas are eroded limestone with coral and shell fragments.
– Some sands contain magnetite, chlorite, glauconite, or gypsum.
– Sand deposits in certain areas contain garnets and small gemstones.
– Sand is formed from the weathering of rocks mainly by water and wind erosion.
– Sand from rivers and flood plains is the primary source for construction.
– Sand dunes are formed in dry conditions or by wind deposition.
– The Sahara Desert has vast sand dunes due to lack of vegetation and water.
– Beach sand is formed by erosion, weathering, river deposition, and marine interactions.

**Uses and Demand:**
– Sand is used in high demand for making concrete.
– Beach sand and fossil sand are extensively used for construction.
– Desert sand is not suitable for concrete due to its properties.
– Sand mining in rivers causes environmental concerns and economic losses.
– Wind shapes desert sand to be round and smooth, making it unusable for construction.
– Sand as an abrasive element.
– Sandy soils are ideal for certain crops.
– Sand used in air filtration and aquaria.
– Sand essential in concrete, glass, and mortar.
– Sand employed in landscaping, roads, and recreation.

**Resources, Environmental Concerns, and Hazards:**
– Some sands not suitable for construction.
– Demand for construction sand depleting natural sources.
– Impact of sand mining on marine life and ecosystems.
– Environmental concerns over dredging industry.
– Countries banning sand exports due to environmental issues.
– Silica sand used in sandblasting poses health risks.
– Respiratory protection recommended for sandblasting.
– Excessive inhalation of crystalline silica is a health concern.
– Safety data sheets warn of health risks from silica dust.
– Precautions necessary for sand-using activities such as sandblasting.

**Manufacture and Case Studies:**
– Manufactured sand (M sand) is made from rock through artificial processes for construction purposes in cement or concrete.
– M sand is more angular compared to river sand and possesses slightly different properties.
– Dubai, UAE has high demand for sand in infrastructure and island construction, leading to the use of over 835 million tonnes of sand in projects costing more than US$26 billion.
– Sand reserves in Dubai were depleted, necessitating the import of sand from Australia for construction projects.https://en.wikipedia.org/wiki/Sand