![]() The other 20 or so (with atomic numbers 104-118 and 99-103) elements are artificial – they are synthesized in nuclear reactors and some are radioactive with very short lives. The chart contains 118 elements in all, but only about 90 occur naturally. In this table, elements are in numbered periods (rows) and groups (columns) based on the configuration of their electron orbitals. Oganesson is an obscure synthetic radioactive element that has only been produced a few times and in minute amounts. The first element is hydrogen (atomic number 1) and the last is oganesson (atomic number 118). Elements are ordered by increasing atomic number (the number of protons in their atom nucleus), which correlates with atomic weight and size. Here (Figure 2.3) we see the Periodic Table of the Elements. 2.2 Elements and the Periodic Table 2.3 The Periodic Table of the Elements Similarly, rocks containing significant amounts of phosphorous usually contain apatite, Ca 5(PO 4) 3(OH,F,Cl), or monazite, (Ce,La,Th,Y)PO 4. Rocks rich in Ti always contain one of these latter three minerals. In many rocks, however, Ti is concentrated in Ti-rich minerals such as rutile (TiO 2), titanite (CaTiSiO 5), and ilmenite (FeTiO 3). For example, titanium (Ti) may occur as a minor component in biotite, amphibole, or other minerals. In contrast, because of their properties, some other elements tend to be found in only a few distinct minerals. Many sedimentary rocks and nearly all igneous and metamorphic rocks are composed of multiple minerals containing these two elements. Oxygen and silicon are perhaps the best examples. Some elements are common in many different minerals. Nonetheless, in most settings, we can expect common minerals to be made of the elements shown in the histograms above. And, the composition of the shallow crust is somewhat different from the deep crust. For example, the oceanic crust is not the same composition as the continental crust. The compositions of Earth’s outer layers vary somewhat laterally and vertically. And other generally rare elements are sometimes concentrated by geological process to make exotic minerals. Hydrogen (0.15 wt%) and carbon (0.18 wt%) are overall minor elements in the crust but are key components in some minerals. However, the mantle contains much more magnesium and iron, and less silicon, than the crust. Other quite abundant elements in both the crust and mantle include aluminum, iron, calcium, sodium, potassium, and magnesium. Together these two elements make up about three quarters of the crust, and two thirds of the mantle. In both places, oxygen and silicon are the dominant elements (Figures 2.2 and 2.3). Most of the minerals and other geological materials we see derive from the crust, but some come from the uppermost part of the mantle. And, the core is completely different from the crust and mantle – it is mostly iron with perhaps 20% nickel and lesser amounts of other elements. Although Earth’s crust and mantle contain the same major elements, the proportions are not the same (see histograms below). Earth, however, is dominated by other elements, and 8 to 10 elements account for most of Earth’s mass. For example, the matter of the Milky Way, our galaxy, is mostly hydrogen and helium – the same elements that make up >99% of our sun. Although 1000s of minerals are known, only a small number are common.Īll matter is made of atoms of individual elements.Weight % values can be normalized to give chemical formulas.We describe mineral compositions by giving weight %s of the elements or oxides present.The kind of bonding affects mineral properties.Ionic, covalent, or metallic bonding are most common in minerals.Elements with similar properties may substitute for each other in minerals and many minerals have variable compositions.The Periodic Chart of the Elements orders elements by their atomic number and groups elements with similar properties.8 to 10 elements account for most of Earth’s mass but the elements are distributed unevenly.All matter, including mineral matter, is made of elements.2.1 Carrollite has the formula Cu(Co,Ni) 2S 4
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