Section 1. P 7

— > —, extremely rich in pyroxene, perpyric. O 1

2. P 7 5 — < — > —, dominant pyroxene, dopyric. O 1 3

3. P 5 3 — < — > —, pyroxene and olivine, equal or nearly equal, pyrolic. O 3 5

4. P 3 1 — < — > —, dominant olivine, domolic. O 5 7

5. P 1 — < —, extremely rich in olivine, perolic. O 7

In the last two orders a distinction between the preponderant mitic minerals is recognized by suborders, five in number. The minerals containing Fe₂O₃ are compared with those containing TiO₂. The former, magnetite and hematite, are called hemic, mnemonic of hematite; the latter subgroup, titanite, ilmenite, perofskite, rutile, are called tilic, mnemonic of titanite and ilmenite. Of orders 4 and 5, there are

Suborder 1. H 7 — > —, hemic minerals extreme, perhemic. T 1

2. H 7 5 — < — > —, dominant hemic minerals, dohemic. T 1 3

3. H 5 3 — < — > —, hemic and tilic minerals equal or nearly equal, T 3 5 tilhemic.

4. H 3 1 — < — > —, dominant tilic minerals, dotilic. T 5 7

5. H 1 — < —, tilic minerals extreme, pertilic. T 7

Further subdivision, producing rangs and subrangs, is made on the character of the chemical bases in the standard minerals used in forming orders and is expressed in terms of the molecular proportions of certain oxides. For the salic minerals, forming orders in the first three classes, the bases are alkalies—K₂O and Na₂O—and lime, CaO. For the femic minerals, forming orders in the last two classes, the bases are MgO, FeO, CaO and alkalies, K₂O, Na₂O. In classes I, II, and III rangs are formed by comparing salic alkalies, K₂O′ + Na₂O′, with salic lime, CaO′; and subrangs are formed by comparing K₂O′ with Na₂O′.

Rang 1. K₂O′ + Na₂O′ 7 ——————————— > —, alkalies extreme, peralkalic. CaO′ 1

2. 7 5 „ < — > —, alkalies dominant, domalkalic. 1 3

3. 5 3 „ < — > —, alkalies and lime equal or nearly so, 3 5 alkalicalcic.

4. 3 1 „ < — > —, lime dominant, docalcic. 5 7

5. 1 „ < —, lime extreme, percalcic. 7

Subrang 1. K₂O′ 7 ———— > —, potash extreme, perpotassic. Na₂O′ 1

2. 7 5 „ < — > —, potash dominant, dopotassic. 1 3

3. 5 3 „ < — > —, potash and soda equal, sodipotassic. 3 5

4. 3 1 „ < — > —, soda dominant, dosodic. 5 7

5. 1 „ < —, soda extreme, persodic. 7

In classes IV and V rangs are formed by comparing femic MgO + FeO + CaO″ with femic alkalies K₂O″ + Na₂O″.

Minerals containing magnesia, iron, and lime are called mirlic.

Rang 1. MgO + FeO + CaO″ 7 ———————————————— > —, extremely mirlic, permirlic. K₂O″ + Na₂O″ 1

2. 7 5 „ < — > —, dominantly mirlic, domirlic. 1 3

3. 5 3 „ < — > —, equally mirlic and alkalic, alkalimirlic. 3 5

4. 3 1 „ < — > —, dominantly alkalic, domalkalic. 5 7

5. 1 „ < —, extremely alkalic, peralkalic. 7

Sections of rangs distinguish between MgO + FeO and CaO″. Minerals with MgO + FeO are called miric.