Salts of sulfuric acid H2SO4. Sulfates are generally a good material for growing crystals, because of their stability and solubility.
Sulfuric acid also forms salts or adducts with some organic compounds and complex ions.
Double sulfates: Tutton's salts
There are many sulfates that have 2 different metals in it, in stoichiometric proportion. They form several families of similar compounds. Tutton's salts are compounds of general formula: MI2MII(SO4)2·6H2O, where MI and MII stand for univalent and bivalent anions. In mineralogy, they are called schoenites.
- Ammonium zinc sulfate (NH4)2Zn(SO4)2·6H2O
- Potassium zinc sulfate K2Zn(SO4)2·6H2O
- Ammonium iron(II) sulfate (NH4)2Fe(SO4)2·6H2O, also known as Mohr's salt.
- Potassium magnesium sulfate KMg(SO4)2·6H2O, mineral schoenite.
- Mixed K-Mg and K-Cu schoenite, K2(Mg0.5Cu0.5)(SO4)2·6H2O
Double sulfates: bloedite family
Bloedites are similar to Tutton's salts (schoenites), but have 4 molecules of water instead of 6. They also can include Na ions.
- Sodium zinc sulfate Na2Zn(SO4)2·4H2O, mineral Changoite.
Double sulfates: alums
Alums are the family of similar double sulfates of general formula: MIMIII(SO4)2·12H2O, where MI and MIII stand for univalent and trivalent anions. MI is usually one of K, NH4 but can be other: Na, Rb, Tl. Trivalent metal MIII is usually one of Al3+, Fe3+, Cr3+.
- Potassium Aluminum sulfate KAl(SO4)2·12H2O, usually called just "alum" or potassium alum. The most representative member of this family.
- Ammonium Aluminum sulfate NH4Al(SO4)2·12H2O, less common compound that is visually indistinguishable from the potassium salt.
- Ammonium Iron(III) sulfate NH4Fe(SO4)2·12H2O, or ferric alum.
Salts of phosphoric acid H3PO4.
- Ammonium dihydrogen phosphate NH4H2PO4. A common fertilizer, giving nice columnar crystals.
Salts of acetic acid. Most acetates are soluble, but few of them are suitable for growing nice crystals.
Salts of nitric acids HNO3. Most of nitrates are extremely soluble in water and deliquescent, which makes them badly suited for growing.
- Ammonium calcium nitrate 5Ca(NO3)2·NH4NO3·10H2O
- Sodium chloride NaCl, table salt (very hard to grow)
- Potassium chloride KCl, much better growing potassium sibling of table salt.
- Ammonium chloroferrate (NH4)2[FeCl5(H2O)], mixed chloride or ammonium and iron (III).
- Potassium tris(oxalato) aluminate K3[Al(C2O4)3]
Ferrioxalates have beautiful green color, unusual for iron (III) compounds. THey are slightly light sensitive.
- Sodium tris(oxalato) ferrate(III) Na3[Fe(C2O4)3] - unstable but beautiful green crystals
- Potassium tris(oxalato) ferrate(III) K3[Fe(C2O4)3] - green crystals, more stable to dehydration than sodium salt.
- Sodium potassium tris(oxalato) ferrate(III) K5Na[Fe(C2O4)3]2 - anhydrous crystals of deep green color, lesser known relativeof the above two salts. Very recommended for growing!
- Erythritol C4H10O5 another sugar alcohol, lighter cousin of a xylitol.
- Xylitol C5H12O5 sugar alcohol, used as sugar substitute.
- MannitolC6H14O6 another sugar alcohol.
- Glucose sodium chloride 2C6H12O6·NaCl·H2O cocrystal of glucose and table
- Glucose sodium bromide 2C6H12O6·NaBr·H2O heavier sibling of the above compound, cocrystal of glucose and NaBr
- Urea citrate CO(NH2)2·C3H4(OH)(COOH)3 cocrystal of urea and citric acid.
- Glutamic acid hydrochloride C3H5(NH2)(COOH)2·HCl
- Saccharin Free acid of saccharin, insoluble in water.
- Sodium saccharin Sodium salt of saccharin, once popular sugar substitute.