What are the 8 properties used to identify minerals?
Regional SpecificsMost minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity. What are the 10 mineral properties? These include: color, streak, hardness, luster, diaphaneity, specific gravity, cleavage, fracture, magnetism, solubility, and many more. These physical properties are useful for identifying minerals. What are the
What are the 4 eras of Earth history?
Regional SpecificsEarth’s history is characterized by four eons; in order from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. What are the 4 major eras in Earth’s history in order? The Precambrian, Paleozoic, Mesozoic, and Cenozoic Eras The Geologic Time Scale is the history of the Earth broken down into four spans of
Why are sedimentary rocks The most important rocks for humans?
Regional SpecificsSedimentary rocks are also important sources of natural resources including coal, fossil fuels, drinking water and ores. The study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth’s history, including palaeogeography, paleoclimatology and the history of life. Why is sedimentary important? Sediment is important because it often
What is the most explosive type of magma?
Regional SpecificsThe largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas (dacite and rhyolite). What is explosive magma? Explosive eruptions occur where cooler, more viscous magmas (such as andesite) reach the surface. Dissolved gases
What type of cleavage does hornblende have?
Regional SpecificsImperfect Hornblende Crystal habit Hexagonal/granular Cleavage Imperfect at 56° and 124° Fracture Uneven Mohs scale hardness 5–6 How many cleavage does hornblende have? two perfect cleavages Hornblende is black and, like all amphibole minerals, is characterized by two perfect cleavages that intersect at about 60° or 120°. Does hornblende have good cleavage? Hornblende minerals as
How old are humans in relation to the age of the Earth?
Regional SpecificsWhile our ancestors have been around for about six million years, the modern form of humans only evolved about 200,000 years ago. Civilization as we know it is only about 6,000 years old, and industrialization started in the earnest only in the 1800s. How long have humans been on Earth compared to the age of