1. Alkaline earth metals

2. Beryllium (Be)
Universe: ppm (by weight) 
Sun: ppm (by weight) 
Carbonaceous meteorite: 0.03 ppm 
Earth's Crust: 2.6 ppm 
Seawater: 0.02 ppm

3. Beryllium in magmatic processes
In magmatic differentiation it enriches in granite and alkaline magmatic rocks, e.g. nepheline syenite, especially in pegmatitic processes. Small ionic radius (0,34), similar to Si (0,39), and little coordination number (4). Important Be-minerals in pegmatites: beryl, chrysoberyl, phenakite, all silicates. Rare oxide (bromellite), phosphate (berillonite), borate (hambergite), too.
Occassionally appears in skarns and hydrothermal ore deposits (e.g. helvite). It can replaces Al or Si in skarn silicates (garnets, vesuvianite etc.).
The largest Be-accumulation connect to acidic pyroclastic rock (here the main Be-minerals is bertrandite).

4. Beryllium in weathering and sediments
In weathering processes move together with Al, such in clays, bauxites, and recent marine sediments.
It can concentrates in coals (high enrichment in coal ash, too), by absorption in organic matter with REE and other elements (Nb, Ge, V, etc).
It concentrates in plants in biosphere, too.
The salts of beryllium have strong toxicity.

5. Magnesium (Mg)
Universe: 600 ppm (by weight) 
Sun: 700 ppm (by weight) 
Carbonaceous meteorite: 1.2 x 105 ppm  
Earth's Crust: ppm 
Seawater: 1200 ppm

6. Magnesium in magmatic processes
Magnesium is a highly compatible element during mantle melting, and residual mantle is more magnesian than fertile mantle. Magnesium remains a compatible element during crystallization of magmas because olivine, orthopyroxene and/or clinopyroxene are typical liquidus phases. Hence, Mg is concentrated in the Earth's mantle, while in the crust it is most abundant in the oceanic crust and the lower continental crust. Magnesium is a minor or trace element in highly evolved igneous systems, and typical Mg contents of granites are on the order of mg/g.

7. Magnesium in magmatic processes
It appears both simple and complex compounds. It concentrates in ultrabasic-basic magmatites. Characteristic constituent of mafic rock-forming minerals, as forsterite/olivine, Mg/Fe pyroxenes (e.g. enstatite) and amphiboles.
Different abundance was detect about calcium-analogue compounds, such fluorite – sellaite or apatite – wagnerite. However, inverse abundance is well-known, see periclase – lime, or brucite – portlandite pairs.
Characteristic Mg2+ / Fe2+ substitution in all rock-forming minerals. The Mg dominance in high temperature and in calk-alkaline magmatites. On the other hand, Fe dominance appear in most of oxides (except of spinel).
It forms mainly carbonates in post-magmatic processes.

8. Rock-forming Mg-minerals

9. Magnesium in weathering processes and sediments
During weathering of rocks, Mg readily dissolves in the
weathering solutions and enters to the hydrosphere. Magnesium is removed from ocean water by carbonate precipitation, but even so, Mg is a conservative element in seawater. It enriches in marine and freshwater sediments, too. It has similar characteristics than sodium, but differs from calcium. It forms late precipitates (Mg- or Mg-K-salts) in evaporites. Many times it occurs close associates with borates.

10. Magnesium carbonates
It very rare forms directly from seewater or freshwater as dolomite. Much more crystallize in long diagenetic processes.
The Mg carbonates form from limestone by Mg-metasomatism with Mg-rich solutions. In the order of total crystallization: limestone dolomitic limestone  dolomite  magnesite. There are many substitutions in cation position in these carbonates (e.g. Mg2+,Fe2+, Mn2, Zn2) e.g. at Rudabánya ore deposit and some magnesite localities of Szepes-Gömör Ore Mts., Eastern Slovakia.
Mg carbonates (mainly magnesite) crystallize from Mg-rich ultrabasites and metamorphites (e.g. serpentinite) by hydrothermal solutions, too.

11. Dolomitization
In high temperature experiments ( <200°C), following an induction period, dolomitization proceeds rapidly, producing the metastable phases (high Mg calcite) and calcian dolomite before stoichiometric dolomite is formed. Several hydrothermal and metamorphic dolomites are stoichiometric and ordered. However, sedimentary dolomites exhibit different degrees of ordering and compositional ranges. At low, sedimentary temperatures, the types of natural waters appears to occur are characterized by high supersaturation, high Mg/Ca ratio and elevated CO3- and HCO3 concentrations. The dolomite produced is, however, weakly ordered and calcian. Holocene dolomites are fine-grained, poorly ordered, and may contain up to 7-8 mol% CaCO3.

12. Magnesium in biosphere
It forms around 10 pH as hydroxide in soils.
Common microcomponent in low-class plants. Essential componens of high plants, e.g. in chlorophil. It catalytic effects is well-known in photosynthesis. Important activator of some enzyms, too.
Some marine plants, animals (e.g. algae) have high Mg-content. Occassionally determined from skelets of shells and gastropodas. In high-class animals (and the man) common constituent in bones, musculars, and nervous tissues. Mg-containing carbonates and/or phosphates can produce occlusion in venas (e.g. coronary occlusion).

13. Calcium (Ca)
Universe: 70 ppm (by weight) 
Sun: 70 ppm (by weight) 
Carbonaceous meteorite: ppm 
Earth's Crust: ppm 
Seawater: 390 ppm

14. Calcium in magmatic processes
Ca-content of the bulk Earth is variously estimated to be mg/g. Mid-ocean ridge basalts typically contain about 81 mg/g Ca. Calcium becomes a compatible element during crystallization of magmas once plagioclase and/or clinopyroxenes begin to crystallize, and during crustal melting. The Ca contents of typical granites are of the order of 2-18 mg/g. Calcium is concentrated in the oceanic ( ~81 mg/g) and the lower continental (37-67 mg/g) crusts of the Earth.

15. Calcium in magmatic processes
Well-known simple and complex compounds both magmatic and metamorphic rocks. Because of ionic radius of Ca very often forms in the structure of silicates (both mafic and felsic silicates).
Important Ca silicates: Ca-garnets (grossular, andradite) Ca-pyroxenes (augite, diopside, hedenbergite), Ca-pyroxenoides (wollastonite), Ca-amphiboles (actinolite, tremolite, hornblende-family), epidote-group, Ca-micas, (margarite, clintonite), Ca-plagioclase (anorthite), felspatoids (cancrinite, haüyne), Ca-zeolites (laumontite, scolecite, series of heulandite and chabazite).
Special Ca silicates found as characteristic minerals in high temperature skarns (wollastonite, larnite, rankinite etc.).

16. Calcium in magmatic processes
Ca has low abundace in early magmatic differenciates, except anorthite (in anorthosite). However, the basic magmatic rocks, one of main mineral is a Ca-rich basic plagioclase. About the half part of Ca crystallize in later differentiates, as Ca-rich pyroxenes, and amphiboles.
Other Ca-containing compounds, e.g. oxides are accessoric components (e.g. perovskite, pyrochlor-group), they occur mainly in alkaline magmatics.
There are wolframates (scheelite), molibdates (powellite) and especially carbonates (ankerite, dolomite, calcite, aragonite) in post-magmatic origin.

18. Calcium in weathering and sediments
During weathering of rocks, Ca readily dissolves in the
weathering solutions and enters to the hydrosphere.
The ratio of Ca : Na is lower in sediments (e.g. in clays) than magmatic rocks. Ca similar to Na, because it builds in clay minerals in small amounts.
There is a different in Ca-contents between seewater and freshwater (latter contains more Ca, because of quicker weathering of anorthite than albite). Large masses of Ca-carbonates forms in sedimentary environment, in some cases with evaporites.
Latter environment not only carbonates, but Ca-sulphates (gypsum, anhydrite) phosphates (apatite-OH, apatite-Cl, apatite-F) form in large amounts.

19. Calcium carbonate and the carbonic acid system
Calcium carbonate and the carbonic acid system have a major role in the geochemistry of sedimentary carbonates which form, dissolve and reprecipitate at the Earth's surface and in the oceans. Karst dissolution, which shapes the landscape of carbonate terrains, the formation of carbonate platforms and atolls, the dissolution of deep-sea sediments, the development of porosity in limestones and dolomites and its destruction via precipitation of cements in vugs are some of the phenomena depending on the calcium carbonate and carbonic acid system interactions. It forms chemical (direct precipitates from water), and biological (skeletal parts of organisms) ways.

20. Calcium carbonate polymorphs
Calcium carbonate crystallizes in a variety of polymorphic forms. The two most common natural polymorphs are calcite (trigonal) and aragonite (orthorhombic). A third polymorph, vaterite (hexagonal) has been found in gallstones, tissues of fractured gastropod shells and as rare alteration product. The vaterite is very instable phase.

21. Calcium carbonate polymorphs
Under Earth's surface conditions, calcite is the most abundant and thermodynamically stable polymorph of CaCO3. Aragonite is relatively abundant and it is stable polymorph at high pressure. But at surface pressure is unstable and should transform to calcite. Nevertheless, aragonite persists in tectonically uplifted blueschist facies metamorphic rocks, and precipitates both inorganically (e.g. caves) and through biogenic processes to form carbonate platform sediments and cements. Vaterite is always metastable under sedimentary conditions. Magnesian calcites are an important variety of CaCO3, they are an important component of the shallow-water marine sediments either as direct precipitates or as components of the skeletal parts of organisms.

22. Strontium (Sr)
Universe: 0.04 ppm (by weight) 
Sun: 0.05 ppm (by weight) 
Carbonaceous meteorite: 8.9 ppm 
Earth's Crust: 360 ppm 
Seawater: 7.6 ppm   

23. Barium (Ba)
Universe: 0.01 ppm (by weight) 
Sun: 0.01 ppm (by weight) 
Carbonaceous meteorite: 2.8 ppm 
Earth's Crust: 500 ppm 
Seawater:   Atlantic surface: 4.7 x 10-3 ppm    
Atlantic deep: 9.3 x 10-3 ppm    
Pacific surface: 4.7 x 10-3 ppm    
Pacific deep: 2 x 10-2 ppm

24. Strontium and barium in magmatic processes
They rarely form indepentent minerals in magmatic processes (e.g. barium feldspars, the celsian-paracelsian-hyalophan series).
In common rock-forming minerals the Sr2+ substitutes Ca2+ (e.g. plagioclases, apatites, pyroxenes), while Ba2+ replaces K+ (mainly in alkali feldspars, micas).
The barium content in magmatic rocks normally increases with increasing SiO2 concentration. Granitic rocks with high Ca concentrations are generally enriched in barium, and alkaline rocks are usually highly enriched in strontium.

25. Strontium and barium in magmatic processes
Low abundaces in pegmatithic and pneumatolithic phases. In contrary, hydrothermal processes they show higher abundances with many independent minerals.
Examples of Sr: celestite, strontianite, svanbergite, and Sr-zeolites (brewsterite-Sr, chabazite-Sr). It substitutes Ca most often in calcite, aragonite, and gypsum.
Examples of Ba: barite, witherite, Ba-zeolites (brewsterite-Sr, harmotome, phillipsite-harmotome solid solutions, edingtonite). It replaces K in alkali feldspars (e.g. adularia in epithermal ore deposits). High frequency of barite – celestite solid solution in hydrothermal processes (so-called baritocelestite).

26. Strontium in weathering and sedimentary environment
After weathering Sr moves more amounts to the hydrosphere, than Ca. In the evaporation it concentrates in gypsum, calcite, anhydrite by substitution, or it forms independent minerals, e.g. celestite. In sedimentary rocks it is predominantly found in carbonate rocks composed of calcite and/or dolomite. It may also be present in carbonate cement. Diagenetic and weathering processes may further distribute and re-distribute strontium among the major rock groups. The amount of Sr found in these rocks, depends on the depositional/diagenetic redistribution of Sr with Ca. In contrast, in other sedimentary rocks the distribution of Sr into feldspars depends on the substitution with K.

27. Barium in sedimentary environment
In many natural environments, aqueous barium concentrations are controlled primarily by ion exchange and sorption reactions. Also important in the aqueous geochemistry of barium is the low solubility of barite. In alkaline systems, the soluble nature of witherite can control barium mobility.
It has better absorption characteristics than strontium, so it moves lesser amounts to oceans. The Sr : Ba ratio in magmatic rocks is 0.6, while in the seewater is 260.
In sedimentary rocks, barium normally occurs as barite, or in clays, and in feldspars. Barium can accumulates in manganese oxides in soil and ferromanganese nodules in the oceans.

28. Barium and strontium in sedimentary environment and biosphere
Celestite and strontianite common sedimentary Sr-minerals, but they occur always in small amounts. Sr in soils: it concentrates high amounts if Ca-content is higher. Occassionally forms mainly as celestite or strontianite. The precipitation of Ba-Sr sulphates are controlled by microorganism, too. Sr (and rare Ba) occurs in small amounts in skelets of organics.