MINERALOGY. 



iS 



When they have been worn by the 

 action of the sea they are very smooth 

 and shining. Like other shells they 

 are composed of carbonate of lime. 

 When placed in a weak acid such as 

 vinegar, a chemical change takes place, 

 carbonic acid gas is given off and in 

 its escape produces the movements 

 which are popularly supposed to show 

 that the stone is "alive." 



When one of the stones is placed 

 under the eyelid, at the outer corner, 

 the natural movements of the lid in 

 winking push it gradually towards the 

 inner side, and when it comes in con- 

 tact with the mote which is causing 

 the irritation this is carried along and 

 finally expelled with it. 



The belief that such stones have a 

 peculiar detective power and move 

 about in the eye until they find and 

 remove the substance for which they 

 are sent, has no foundation in fact. 



It is interesting to know that in the 

 lining membrane of the stomach of the 

 crawfish there are found small bodies 

 which go under the name of "crab's 

 eves," and look not unlike the true 

 eyestones. They have sometimes been 

 mistaken for them and presumably 

 would serve a similar purpose. 



Collecting Interesting Minerals. 



BY EORACE R. GOODWIN, PHIUPEU'II IA, 

 PENNSYLVANIA. 



Let those of your readers who have 

 not visited the home of an enthusiastic 

 collector of minerals do so at the first 

 opportunity offered and they will be 

 treated to a new experience, spend a 

 pleasant hour, and in many cases 

 become interested in every stone and 

 rock encountered in their rambles 

 afield, with the result that the mineral 

 department of The Guide to Nature 

 will soon be in a flourishing condition. 

 T have been an active collector of 

 minerals for over a quarter of a century 

 and, while not advanced in the science, 

 have used my eyes to some purpose in 

 the field. 



One of my most enjoyable and profit- 

 able experiences was the meeting with 

 the Student's Mineralogical Club, now 

 the Philadelphia Mineralogical Club, 

 on Thanksgiving Day, 1894, in Fair- 



mount Park. The friendships there 

 formed have been of lasting benefit. 



While searching for specimens in 

 a large quarry at Moores Station near 

 Trenton, New Jersey, some- time ago, 

 1 discovered a large cavity in the rock 

 which was lined with beautiful, snow- 



SMOKY QUARTZ 



white crystals of natrolite, a mineral 

 consisting of silica, alumina, soda and 

 water, belonging to the zeolite group 

 and named from natron, soda. Asso- 

 ciated with the acicular crystals of 

 natrolite w r ere rhombic crystals of 

 yellow calcite (carbonate of lime) from 

 one half to one inch in diameter, the 

 combination of the two minerals being 

 very attractive. Although the material 

 is very fragile a number of fine speci- 

 mens were secured and are now safely 

 housed in my cabinet. 



Numerous other minerals occur at 

 this locality, among them being 

 stilbite, both white and honey colored, 

 sometimes coated with iridescent pyrite; 

 calcite of various forms, chalcopyrite, 

 prehnite, galena, chalcedony and 

 several others that I cannot now recall. 



On another occasion while digging 

 for quartz in a sand pit at Lansdowne, 

 Delaware County, Pennsylvania. I 

 unearthed a fine large crystal of smoky 

 quartz that weighs thirteen and three- 

 quarters pounds and is as fine a speci- 



