| IFA |
| See Institute of Field Archaeologists. |
| Igneous |
| Most igneous rocks have crystallised (solidified) from a magma (liquid) state and are either pushed out on the surface as volcanoes (extrusive) or pushed into the rocks forming the earth?s crust (intrusive).
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| Igneous rocks |
| Hard and tough crystalline rocks, formed from primary silicate melts which may be coarse-grained (e.g. granite, dolerite, gabbro, granodiorite, etc.) or fine-grained (e.g. basalt or rhyolite). |
| Impact |
| The act of striking or colliding with a rigid surface. |
| Impact crusher |
| This is a crusher which uses impact. It usually consists of metal bars (known as beaters, impellors, hammers or blow bars) attached to fixed rotors on a rotating shaft within a crushing chamber lined with metal impact plates or bars (known as anvils or breaker plates). |
| Impact strength |
| Force of impact (striking or colliding with) required to break material. |
| Impellors |
| The fixed rotors within an impact crusher, also known as beaters or blow bars. |
| Impermeable |
| A rock is impermeable if water cannot pass through it.
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| Indirect dryers |
| System for drying dewatered solids by passing them over a surface heated by internally circulated hot fluid. The solids never contact the actual heat source, thus avoiding contamination. |
| Indirect impacts |
| impacts on the environment, which are not a direct result of the development but are often produced away from it or as a result of a complex pathway. Sometimes referred to as secondary impacts. |
| Industrial minerals |
| Non-metallic non-energy minerals used in a very wide variety of applications. The term generally excludes construction materials such as aggregates and stone. Examples include clays, fluorspar, salt and gypsum. |
| Inelastic behaviour |
| A state where a solid does not recover to its original shape and volume following deformation under stress, but remains permanently deformed. |
| Inert |
| Material which will not react with or be significantly altered by other material. It is stable. |
| Inert Dust |
| Dust composed of material with no clinically proven effects on health. |
| Institute of Ecology and Environmental Management |
| IEEM is the professional Institute supporting professionals in the fields of ecology and environmental management. www.ieem.org.uk. |
| Institute of Environmental Management and Assessment |
| IEMA is a not-for-profit organisation established to promote best practice standards in environmental management, auditing and assessment. www.iema.net |
| Institute of Field Archaeologists (IFA) |
| The Institute of Field Archaeologists is the professional organisation for archaeologists in the UK. It promotes professional standards and ethics for conserving, managing, understanding and promoting enjoyment of the heritage. www.archaeologists.net.
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| Integrated Pollution Control (IPC) |
| Integrated Pollution Control is the process specified by the Environmental Protection Act 1990, for the control of polluting emissions into the three environmental media of land, air and water. Strictly speaking IPC is restricted to Part A processes under the jurisdiction of the HMIP. Environment Agency Info.
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| Integrated Pollution Regulation (IPR) |
| Integrated Pollution Regulation, see Chief Inspectors Guidance for HMIP Inspectors, Series 3 (mineral sector). |
| Interburden |
| Unwanted material between the layers or veins of desired mineral. For instance the layers of rock between coal seams. The term is mainly used in surface mining. |
| Intergranular Flow |
| Groundwater which moves along irregular pathways through void spaces, between loose sediments.
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| IPC |
| See Integrated Pollution Control. |
| IPR |
| See Integrated Pollution Regulation. |
| Iron Age |
| In Britain the period approximately between 700BC and the Roman conquest. Equated with the introduction of iron technology. |