172 THE NATURE STUDY COURSE. 



lessons on ice and mica, limestone and quartz, and a topical 

 scheme for the deeper study of any mineral. At the start, 

 choose from the scheme the topics that present the least 

 difficulty in investigation and expression ; gradually increase 

 the number and difficulty of the observations and experiments. 

 The pupil's vocabulary of technical terms will enlarge and 

 clarify with experience. Terms and definitions either here or 

 elsewhere should not be taught in advance of their use. 

 Paddock's "Mineral Schedules" 1 bear the following headings: 

 hardness, form, structure, cleavage, fracture, tenacity, color, 

 streak, lustre, diaphaneity, touch, magnetism, electricity, 

 specific gravity (or weight), chemical properties, composition, 

 formula, classification, tests, variety, uses, how extracted, 

 natural history. The series of minerals which that teacher 

 recommends, arranged in the order of hardness, is : 1, steatite, 

 graphite; 2, gypsum, rock salt, mica; 3, limestone, coal, 

 cryolite, galena; 4, fluorite, azurite, zincite; 5, apatite, 

 hematite ; 6, feldspar, magnetite, pyrite ; 7, quartz. 



Sample Lesson on Coal. — The expression of a study of 

 anthracite, for example, along these lines would read something 

 like this : 



Hardness. — It can be scratched with the point of a pin j it 

 cannot be scratched at all with the finger nail, therefore it is 

 between 2 and 3, 



Scale. — 1, talc or steatite, scratches easily with the finger nail; 2, 

 gypsum, scratches hardly with the finger nail ; 2^, mica, scratches 

 with copper wire ; 3, calcite, scratches with point of pin ; 4, fluorite, 

 scratches easily with point of a well-tempered knife blade ; 5, apatite, 

 scratches hardly with point of knife or hard glass ; 6, feldspar, scratches 

 with a file ; 7, quartz, hardly with corner of hard file ; 8, topaz ; 9, 

 sapphire or corundum ; 10, diamond. 



1 " Minerals in the Public Schools," No. 1, a Pupil's Manual with Outline Blanks, by 

 M. H. Paddock, Proridenoe, R.I., 25o. 



