S-block metals

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s-block metals as material filler

The lighter ones of the alkali- and alkaline earth metals (the non-noble metals in the left s-block of the periodic table) belong to the most abundant elements around. Thus its an iteresting question wheter those elements can be combined with other abundant ones to make structural building materials.

solubility issue

The s-block metals need to be combined with other elements not only because metals are not very suitable for mechanosynthesis but also because they are extremely reactive in pure form. A self passivation oxide layer film like the one that macroscopic blocks of magnesium have is obviously not possible on nano sized building blocks. In contact to air oxidation would go down right to the core of the building block and blow up the part twice in volume destroying it completely.

Since s-block metals are so electropositive they tend to toss away their shell electron or pair of shell electrons and thus tend to form ionic salts. Such a salt usually has the form:

  • positively charged s-block-metal + negatively charged nonmetal-acid

Polar salts of this form are easily dissolved in water since water is a polar solvent. But good water solubility is not what one usually wants from a typical building material - especially not if the solvent is toxic like it is the case with many beryllium compounds. So the focus here will be on the few non or barely water soluble compounds.

barely soluble salts (*ates)

harder compounds (silicates only?)

  • MgSiO3 enstatite [1] Mohs 5-6
  • CaSiO3 wollastonite [2] Mohs 4.5-5

Some harder silicate compounds containing aluminum too are:

  • LiAl(SiO3)2 spodumene [3] Mohs 6.5-7 (contains unabundant lithium) -- monoclinic
  • LiFe(SiO3)2 lithium aegirine (not ocuuring naturally?)
  • KAl(SiO3)2 leucite [4] Mohs 5.5-6 -- tetragonal dipyramidal -- with crystal water: analcime [5] Mohs 5-5.5
  • KFe(SiO3)2 potassium aegirine (not ocuuring naturally?)
  • NaAl(SiO3)2 jadeite (a chain/band silicate) [6] Mohs 6.5-7 -- monoclinic
  • NaFe(SiO3)2 aegirine [7] Mohs 6 -- monoclinic -- there is a variety called "acmite"

  • NH4[AlSi3O8] buddingtonite [8] Mohs 5.5 (insoluble ammonium compound!)
  • Li[AlSi3O8] (unknown? - in literature - are there crystals?) -- monoclinic
  • K[AlSi3O8] orthoclase [9] (feldspar member, monoclinic) Mohs 6 (defining mineral) and amazonite [10] Mohs 6-6.5 and sanidine (endmember?) [11] Mohs 6 and microline [12] Mohs 6-6.5
  • Na[AlSi3O8] albite (sodium placgioclase feldspar) [13] Mohs 6-6.5

  • LiAlSi4O10 petalite [14] Mohs 6-6.5
  • KAlSi4O10 (unknown? potassium petalite)
  • NaAlSi4O10 sodium petalite

  • CaAl2Si2O8 anorthite (calcium plagioclase feldspar) [15] Mohs 6
  • MgAl2Si2O8 magnesium aluminosilicate (there are various associated hydroxide minerals => solubility?)
  • Fe or Cr replacing Al => unknown

Garnets containing aluminum:

  • Ca3Al2(SiO4)3 grossularite [16] Mohs 7-7.5 (an ugrandite garnet and nesosilicate)
  • Mg3Al2(SiO4)3 pyrope [17] Mohs 7-7.5 (a pyralspite garnet and nesosilicate)

Ugrandite garnets are defined by their calcium content:

  • Ca3Al2(SiO4)3 grossularite Mohs 7-7.5
  • Ca3Fe2(SiO4)3 andardite [18] Mohs 6.5-7
  • Ca3Cr2(SiO4)3 uvarovite [19] Mohs 6.5-7 (contains unabundant chromium)

Magnesium analogs to ugrandite garnets:

  • Mg3Al2(SiO4)3 pyrope Mohs 7-7.5
  • Mg3Fe2(SiO4)3 (unknown?)
  • Mg3Cr2(SiO4)3 Knorringite [20] Mohs 6-7

  • NaCa2Si3O8(OH) calcium sérandite [21] Mohs 5-5.5

harder compounds (phosphates)

  • LiFePO4 triphylite [22] Mohs 4-5
  • LiMnPO4 lithiophilite [23] Mohs 4-5 (unabundant manganese)
  • KFePO4 (unknown??)
  • NaFePO4 maricite [24] Mohs 4-4.5
  • (Li,Na)AlPO4(F,OH) amblygonite (endmembers) [25] Mohs 5.5-6
  • MgAl2(PO4)2(OH)2 magnesium lazulite [26] Mohs 5.5-6
  • CaAl2(PO4)2(OH)2 gatumbaite Mohs 4-5

softer compounds (carbonates and otehrs)

When systematically building combinations of s-block metals and d-block nonmetal acids one can find some barely soluble compounds:

  • calcium carbonate CaCO3 (limestone/chalk ... calcite/aragonite/vaterite)
  • dolomite CaMg(CO3)2 [27] Mohs 3.5-4
  • calcium phosphates (similar to hydroxyapatit bone tooth-enamel)
  • calcium silicate CaSiO3 (dry wall plates ... wollastonite)
  • magnesium silicate Mg2SiO4 (forsterite - no crystal water - pretty hard - neosilicate - earth mantle mineral)
  • magnesium silicate Mg3Si4O10(OH)2 (talc - a hydroxide - way too soft for a building material)

Beryllium silicates:

  • beryl Be3Al2(SiO3)6 (cyclosilicate) wikipedia
    varieties: emerald (green Cr), aquamarine (blue Fe), red beryl (red Mn), goshenite (colorless), heliodor (yellow Fe), and morganite (pink Mn)
  • phenakite Be2SiO4 (neosilicate)
  • bertrandite Be4Si2O7(OH)2 (hydorxide - pretty hard - sorosilicate)

non salts but (*ides)

Probably the simplest barely soluble earth alkali compounds (that are not salts) are:

  • MgO (periclase ... magnesia) magnesium oxide (nontoxic)
  • CaF2 (fluorite) calcium fluoride
  • BeO (brommelite Mohs 9) [28] beryllium oxide
  • BeAl2O4 chrysoberyl
  • MgF2 Sellaite (very slightly soluble - unhealthy) [29]

[todo:]

  • [find some insoluble alkali compounds Li Na K]
  • [maybe find some compounds of the heavier and less abundant ones (Rb & Cs) (Sr & Ba)]
  • [treat aluminum as special case]

Related

External links

  1. Wikipedia:Enstatite
  2. Wikipedia:Wollastonite
  3. Wikipedia:Spodumene
  4. Wikipedia:Leucite
  5. Wikipedia:Analcime
  6. Wikipedia:Jadeite
  7. Wikipedia:Aegirine
  8. Wikipedia:Buddingtonite
  9. Wikipedia:Orthoclase
  10. Wikipedia(de):Amazonit
  11. Wikipedia:Sanidine
  12. Wikipedia(de):Mikrolin
  13. Wikipedia:Albite
  14. Wikipedia:Petalite
  15. Wikipedia:Anorthite
  16. Wikipedia:Grossular
  17. Wikipedia:Pyrope
  18. Wikipedia:Andradite
  19. Wikipedia:Uvarovite
  20. Wikipedia:Knorringite
  21. Wikipedia:Sérandite
  22. Wikipedia:Triphylite
  23. Wikipedia:Lithiophilite
  24. Wikipedia:Maricite
  25. Wikipedia:Amblygonite
  26. Wikipedia:Lazulite
  27. Wikipedia:Dolomite
  28. Wikipedia:Brommelite
  29. Wikipedia:Sellaite