Bump!
Perhaps I have discovered something about these mysterious green kryptonite crystals of Gypsy's.
I now have a sample of them, and think I have solved the riddle.
Possibly they are glass slag left from some nearby glass manufacturing plant.
(I can't see where Gypsy ever said exactly where she found them!)
I believe this USGS report is dated from turn of the last century, and indicates significant glass making activity.
Kinda fun, because it lends a bit of possibly historic origin to Gypsy's Green Rocks.
The first paragraph identifies deposits across a number of states, and the last paragraph I've clipped here specifically identifies green bottle glass and places it has been produced significantly.
GLASS SAND OF THE MIDDLE MISSISSIPPI BASIN.
By Ernest F. Bukchakd.
INTRODUCTORY STATEMENT.
A conservative, estimate of the value of the glass products manufactured in the United States in 1905 is in round numbers $55,000,000. The cost of material used approximates $18,000,000, and in this the cost of glass sand was somewhat more than $1,000,000, exclusive of freight charges. Within the half century preceding 1900 the value of glass products showed an average increase of 70 per cent for each decade, and the growth is still vigorous. In view of the remarkable development of an industry so largely dependent for its raw materials on mineral deposits, a brief study has been made of the principal sand-producing areas of the middle Mississippi basin and of their relations to manufacturing centers in the same district. Undeveloped sands in Arkansas, Missouri, Kansas, Wisconsin, and Iowa have been examined in connection with geologic surveying in progress in those States. It is hoped that the information published in this and the preceding paper may be of service to owners of land on which deposits of sand are found and to persons engaged in the production or use of glass sand who may wish to know where further supplies of the material may be obtained.
Topographic maps covering the greater part of all the areas mentioned herewith and geologic maps covering a small part of the same have been issued by the survey. Lists of these'maps are given in the sections devoted to the respective areas.
In the paper "Requirements of sand and limestone for glass making," pages 452-458 of this bulletin, are outlined those characteristics which render a sand suitable or unsuitable for making glass, and in tabular form data are presented concerning the chemical composition and physical character of several sands at present in successful use. Below are given similar data regarding sands of hitherto unknown or doubtful value.
To the producer the questions of physical conditions affecting quarrying and milling, of the amount of available sand, and of location with respect to transportation routes and to markets are as important as that regarding the quality of the sand. Some details are therefore given in the descriptions of properties which illustrate conditions and limitations of successful operation.
GLASS-MAKING INDUSTRY OF THE REGION.
In connection with the examination of sand plants several representative glass factories were visited. Glass of four general classes—plate, window, green bottle, and flint— is made in the middle Mississippi basin from materials obtained, for the most part, in the region. The majority of the glass factories are grouped into two districts—the St. Louis district and the southeastern Kansas district. Fuel and raw materials are naturally the controlling factors in the location of glass plants, and of the two the proximity of fuel seems to be regarded as the more important. Where coal is the basis of the fuel, if it requires 1 ton of coal to 1 ton of glass, nearly as much coal by weight as raw material lias to be transported, yet the freight rates on sand, lime, and salt cake are decidedly higher than on coal...
And here's the page cite, if anyone wishes to learn more about glass making in the Middle Mississippi Basin...
http://books.google.com/books?
id=bB0MAAAAYAAJ&pg=PA460&lpg=PA460&dq=glass+bottling+plants+in+kansas&source=web&ots=vm-ctqdxeg&sig=pvQ0I64Np7hrBENfYDWwsyeOXzw&hl=en&sa=X&oi=book_result&resnum=10&ct=result#PPA460,M1
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