| Gauge |
| Generic term for those devices used to collect atmospheric dust for assessment, such as the gauges specified by BS 1747 (see Deposit gauge). |
| Geophones |
| These are sensors which detect vibration in the ground and can convert it into a voltage which can then be recorded and analysed. |
| Geophysical anomaly |
| The result from a geophysical survey which reveals something that is unexpected which could mark the presence (or absence) of a particular feature.
|
| Geophysics |
| This is the study of the physics of the earth. Geophysical survey techniques use physical properties themselves (e.g. magnetism) or apply properties to see how the earth affects them (e.g. radar), to determine something about the earth structure.
|
| Glass Slide |
| An obscurance gauge first described by Brooks and Schwar (1986). In simple terms a clean glass slide is exposed to the atmosphere for a period of time. The subsequent loss of surface glossiness, due to soilage by dust deposition, is then measured. |
| Glossary |
| A collection of explanations, a partial dictionary for a special purpose. |
| Good practice |
| The ideal strategy to counter identified adverse effects on procedures or processes using the Best Available Techniques (BAT). This can apply throughout the quarry lifespan, from initial surveys through the production phase to closure and aftercare. |
| Grain boundaries |
| The interface between adjoining grains. They form important surfaces in the theory and practice of crushing, separation and sizing of rock and mineral particles. |
| Granite |
| Coarse-grained igneous rock, composed primarily of quartz and light-coloured minerals: feldspars and micas. |
| Gravel |
| In civil engineering this refers to particulate material ranging in size from coarse sand to large cobbles (see particle size). In current commercial practice, the term gravel (or more correctly coarse aggregate) is used for general and concrete applications to define particles between 4 and 80 mm. |
| Grindability |
| The ease with which material can be broken into small particles. See Bond Work Index. |
| Grinding |
| A process for reducing rock fragments to smaller particles, in which the motion of the machine components is not strictly controlled and may touch.
|
| Grinding path |
| The passage of material through the crushing chamber. |
| Grit |
| BS 6069 (Part 2) defines ?grit? as particulate matter that is larger in size than 75µm in diameter. |
| Grizzly |
| Particular type of robust coarse screen consisting of parallel steel bars with distance pieces. They are often used to moderate crusher feed rates. |
| Groundwater |
| Water occupying openings, cavities, and spaces in the rocks and soils. Meteoric water is the most common and is due to rainfall having soaked into the rock, while juvenile water rises from a deep magmatic source.
|
| Gyratory crusher |
| Similar to cone crushers; the main difference is that they are typically used in a primary crushing role, whereas cone crushers are used in a secondary or tertiary crushing role. Gyratories operate at a slower speed than cone crushers, typically in the range 85 to 105 rpm. The main shaft is usually suspended from an overhead 'spider', rather than supported from below as with cone crushers. |