page_title: Alkali metal
section_title: On Earth
hierarchical_section_title: Alkali metal / Occurrence / On Earth
caption_attribution_description: English: Spodumene Locality: Walnut Hill Pegmatite Prospect, Huntington, Hampshire County, Massachusetts, USA (Locality at mindat.org) Size: cabinet, 14.2 x 9.2 x 3.0 cm Spodumene This is the CRYSTAL TYPE LOCALITY for spodumene, apparently. A LARGE, 660-gram single, sharply terminated crystal of spodumene from this classic old locality circa mid-1800s! They were considered very important at the time (remember, gem pink kunzite had NOT yet been found in California, Brazil, or Afghanistan), and these crystals were considered highly important and sold or traded into all major museums. Owning one of these would be a goal to assemble any major collection of the time, of important US minerals. Today, they are not worth their weight in gold any more (660 grams...ouch!), but they still are important historical pieces. This location was first documented by Edward Hitchcock in 1833 (Report on the Geology, Mineralogy, Botany and Zoology of Massachusetts), and the first location to yield crystallography on the species (1879). The quarry was last operated by B. K Emerson of Amherst College, and Frank Nason (Nasonite) operated the location in 1885. This is when the majority of the old specimens were recovered. For the size of this crystal, this is really good! They generally get a little more "aesthetically challenged" with size. This is one of the best I have seen, and although color-challenged, it is a very important historical specimen nonetheless, and a superb example from this now defunct pegmatite. ex. Ken Hollman Collection. Thanks to Jim Chenard for this footnote: A funny note on this area was with regards to the early Professor Emerson, who wrote the Mineralogical Lexicon of Hampshire, Hampden Counties in Mass. His journal well documents the Walnut Hill location, and always used taverns as landmarks. His writing got worse during the day, and he would frequently come back to Amherst on foot, since he would forget where his horse was. This is an old location! Deutsch: Spodumen Fundort: Walnut Hill Pegmatite Prospect, Huntington, Hampshire County, Massachusetts, Vereinigte Staaten (Fundort bei mindat.org) Größe: 14.2 x 9.2 x 3.0 cm
context_page_description: The alkali metals consist of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium. Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. This family of elements is also known as the lithium family after its leading element.
  The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen. Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free elements.
context_section_description: The Earth formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the solar system. In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements. The mass of the Earth is approximately 5.98×10²⁴ kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. Due to planetary differentiation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.
  The alkali metals, due to their high reactivity, do not occur naturally in pure form in nature. They are lithophiles and therefore remain close to the Earth's surface because they combine readily with oxygen and so associate strongly with silica, forming relatively low-density minerals that do not sink down into the Earth's core. Potassium, rubidium and caesium are also incompatible elements due to their large ionic radii.
  Sodium and potassium are very abundant in earth, both being among the ten most common elements in Earth's crust; sodium makes up approximately 2.6% of the Earth's crust measured by weight, making it the sixth most abundant element overall and the most abundant alkali metal. Potassium makes up approximately 1.5% of the Earth's crust and is the seventh most abundant element. Sodium is found in many different minerals, of which the most common is ordinary salt (sodium chloride), which occurs in vast quantities dissolved in seawater. Other solid deposits include halite, amphibole, cryolite, nitratine, and zeolite. Many of these solid deposits occur as a result of ancient seas evaporating, which still occurs now in places such as Utah's Great Salt Lake and the Dead Sea. Despite their near-equal abundance in Earth's crust, sodium is far more common than potassium in the ocean, both because potassium's larger size makes its salts less soluble, and because potassium is bound by silicates in soil and what potassium leaches is absorbed far more readily by plant life than sodium.
  Despite its chemical similarity, lithium typically does not occur together with sodium or potassium due to its smaller size. Due to its relatively low reactivity, it can be found in seawater in large amounts; it is estimated that seawater is approximately 0.14 to 0.25 parts per million (ppm) or 25 micromolar. Its diagonal relationship with magnesium often allows it to replace magnesium in ferromagnesium minerals, where its crustal concentration is about 18 ppm, comparable to that of gallium and niobium. Commercially, the most important lithium mineral is spodumene, which occurs in large deposits worldwide.
  Rubidium is approximately as abundant as zinc and more abundant than copper. It occurs naturally in the minerals leucite, pollucite, carnallite, zinnwaldite, and lepidolite, although none of these contain only rubidium and no other alkali metals. Caesium is more abundant than some commonly known elements, such as antimony, cadmium, tin, and tungsten, but is much less abundant than rubidium.
  Francium-223, the only naturally occurring isotope of francium, is the product of the alpha decay of actinium-227 and can be found in trace amounts in uranium minerals. In a given sample of uranium, there is estimated to be only one francium atom for every 10¹⁸ uranium atoms. It has been calculated that there are at most 30 grams of francium in the earth's crust at any time, due to its extremely short half-life of 22 minutes.
caption: Spodumene, an important lithium mineral
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