Sulfates are salts of the sulfuric acid H2SO4. Many of them are a good material for growing crystals, because of their stability and solubility.
- Lithium sulfate, Li2SO4
- Potassium sulfate, K2SO4
- Lithium potassium sulfate, KLiSO4
- Copper(II) sulfate, CuSO4·5H2O
- Sodium ammonium sulfate, NH4NaSO4·2H2O
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.
- Sodium aluminum sulfate NaAl(SO4)2·12H2O is a sodium analog of the above compound. Sodium ion radius is very different from potassium, which makes this alum way less stable.
- 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.
- 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).
- Ammonium tetrachlorocuprate (NH4)2[CuCl4].
Alumooxalates are salts of the complex anion [Al(C2O4)3]3+. They are colorless crystalline solids.
Ferrioxalates are salts of the complex anion [Fe(C2O4)3]3+, they have beautiful green color, unusual for iron (III) compounds. They are slightly light sensitive and must be stored in dark place.
- Lithium tris(oxalato) ferrate(III)Li3[Fe(C2O4)3] - lithium salt of the same green complex, flat crystals.
- Lithium tris(oxalato) ferrate(III) chlorideLi4[Fe(C2O4)3Cl] - double salt with two different anions: ferrioxalate and chloride. Crystals are shaoed as triangular prisms.
- 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!
Sulfamic (also known as amidosulfonic) acid is a moderately strong inorganic acid HSO3NH2. Its primary household use is a descaler agent. Unlike sulfuric acid, it is solid. Almost all sulfamates have extremely high solubility.
- Sulfamic acid, H3NSO3 - the acid itself forms shiny rectangular tablets
- Potassium sulfamate, KSO3NH2, potassium salt for the above acid, crystallizing in a similar shape
- Potassium bis(sulfamato) chlorocuprate, K2[Cu(SO3NH2)2Cl2] - a very interesting sulfamate complex, shiny dark violet sticks
- Potassium bis(sulfamato) bromocuprate, K2[Cu(SO3NH2)2Br2] - bromine analog of the above complex, black tablets with green tinge
- Ammonium bis(sulfamato) chlorocuprate, (NH4)2[Cu(SO3NH2)2Cl2] - ammonium analog, dark blue tablets
- Urea citrate CO(NH2)2·C3H4(OH)(COOH)3 cocrystal of urea and citric acid.
- Saccharin Free acid of saccharin, insoluble in water.
- Sodium saccharin Sodium salt of saccharin, once popular sugar substitute.
Carbohydrates and related compounds
- 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 salt NaCl
- Glucose sodium bromide 2C6H12O6·NaBr·H2O heavier sibling of the above compound, cocrystal of glucose and NaBr
- Glutamic acid hydrochloride C3H5(NH2)(COOH)2·HCl
- Glycyne oxalate 2:1 (NH3CH2COOH)2C2O4 - glycine salt of oxalic acid
- Copper β-alaninate Copper salt of the β-alanine amino acid.
- Copper β-alaninate urea adduct of the above compound with urea. Beautiful dark violet crystals that are stable on air.