Galena, or lead sulphide (PbS), is a shiny grey mineral and the main ore of lead. Also known as Silver-Lead, it can be found in Carboniferous and Palaeozoic rocks around the world. In Britain it is found in Derbyshire, Wales, Upper Teesdale, Weardale, Cornwall, Cumbria, and the Yorkshire Pennines.
Use of this mineral can [...]
The name mica is thought to derive from the Latin word, micare – “to glitter”. This no doubt refers to the brilliant sparkle when light is reflected and refracted by this mineral.
More correctly, the Mica Group of minerals are sheet silicates. This means that instead of growing as a large crystal they form in [...]
Whinstone is a quarryman’s term for a variety of hard, dark-coloured, rocks including basalt and chert. Here, in the Tees Valley and Cleveland, the name refers to a hard rock that is very different from the soft sedimentary strata which make up the majority of the area’s underlying geology.
Around 58 million years ago, as [...]
During his now-infamous journey to the Orient Marco Polo is said to have been amazed when, following meals with wealthy Persians, the tablecloths were cleaned by exposing them to fire the cloths surviving the ordeal without a mark. The fibres from which the cloths were woven came to the Persians from the Hindu Kush, and [...]
Alum Shale occurs within the upper 35 metres or so of the Whitby Mudstone Formation. A suite of rocks that originated as soft sediment accumulating on the floor of an ancient sea (the Tethys) which occupied this area between c.188 million and c.182 million years ago during the late Lower Jurassic phase of Earth’s geological [...]
Sylvite, also called sylvinite when impure, is potassium chloride (KCl) in natural mineral form. It is colorless to white with shades of yellow and red due to inclusions, has a hardness of around 2.5 on Mohs’ Scale and has a distinctively bitter salty taste. Sylvite is a chemical sedimentary rock, laid down through the evaporation [...]
During the Carboniferous period 320 million years ago a large portion of Europe and North America were on the equator. The warm and humid climate was perfect for swampy forests. Occasionally the rivers running through the forests would flood and deposit sand and mud around the base of these plants, burying them whole, [...]
Iron makes up a full 35% of the whole Earth, though most is sequestered within the metallic core, with the crust containing around 6%. It is an important rock commercially, being smelted to make iron and steel. High grade deposits, often comprising more than 70% iron, were laid down in the Precambrian, around 2 billion [...]
Mammoth lived on most of the continents in the Northern Hemisphere during the last big ice age 70-10,000 years ago. Woolly Mammoths were about the same size as Indian elephants are today and covered in a layer of coarse hair. They are a good indicator of a cold climate and tundra or Steppe [...]
Flint is the dark grey to black nodular material commonly found in chalk. It is Cretaceous in age (146-65 million years old). Flint breaks with a pronounced conchoidal (curved) fracture creating sharp edges. This feature was exploited by early man to create edged tools.
It is made up of a mineral called Chalcedony, [...]