358 M:W VnKK STATK Ml'SKUM 



in tlio (lonse ln-usliw ooil. Wlicii (li\\. as i( is diiriiii:: tlio siiinnior 

 soason. ilio ^ii-cam lied may he rci-o^iuizoil wIhmo it leavers the wood 

 and Cillers ilic ilais. liy ilic jH'osencc of imudi calrareons tufa. 

 Tlic iiiiiK' iimv als(» lu* apiu-daclKMl hy a stccj) jiath from ahovo. 

 This begins as a wood i-oad on ilie terrace about 100 feet below 

 the red barn of ^fr Georae Acker on West hill. The ])ath descends 

 over the cliffs abont two tliirds of a mih* beyond Mr Acker's ])lace. 

 The mine is in ihe foi-ni of a fissnrelike tnnnel [sec ]il. 24] and 

 the mineral may be seen in the beds on both sides of the tnnnel 

 in ]ar«>e geodic masses of a milk white color. Some of these hav«» 

 the aspect of having replaced heads of Stromatojiora or oilier 

 fossils. This mineral was formerly known as "marble.'' which it 

 resembles. Calcite, often in the form of nailhead spar, is fonnd 

 in some of the geodes. 



The discovery of the strontianite was announced by Prof. Ebene- 

 zer Emmons in 1835.^ It was at that time the only known deposit 

 of this mineral in the United States. 



The following description of the varieties is by Dr C. U. Shep- 

 ard of Yale Uni versify .^ 



The most obvious variety is that in acicular crystals, and mas- 

 sive in long, straight, divergent individuals. It occurs, occupying 

 irregular cavities, from half an inch to several inches across; the 

 crystals and fibrous masses being implanted upon a dark blue 

 calcareous spar which is granular in large individuals, or crystal- 

 lized in obscure scattered dodecahedra, whose apexes are rej)laced 

 by three, six, nine or 12 faces. The envelope of calcareous sjiar 

 is sometimes of considerable thickness, and is itself often inclu led 

 within the layer of heavy spar, massive in large lamellar individ- 

 uals, some of Avhich penetrate the calcareous spar. But the stron- 

 tianite conslantly rejioses ujion the latter mineral. The crystals 

 are often >}4 of an inch in length, and from the diameter of a 

 pin to that of a hair. The aggregated, columnar individuals fre- 

 quently exhibit at the extremity where they diverge most, crystal- 

 line faces. Some of these fibrous aggregatiouws are two inches in 

 length, and bear a striking resemblance to certain varieties of 

 ai-agonite. .Minnte crystals of iron pyriles, crystallized in the 

 form of pentagonal dmleciiliedrons. are scattered here and there 



'Am. Join-. Sci. isr?."*. 27:1S2. 

 "Am. Jour. Sci. is::.".. '21 ::](\l-(u . 



