3GcS 



pi!(>('i':/:in\r,s or tuf xatiox.il ^fus/':(\^f. 



The prism // )1.'50< iind l)rii<'liypyriiiiii<l -/ )0,1().!)(, besides tlio com- 

 mon rorms,iire siiowii on crystal (lii;'. 1!>). Aiiotiicr (iomhination includes 



t.lic iijin-ow prism M ;123()( between m and /. 



NATlIKor, COJ.oix'Alx). 



Several small crystals are exhibited 

 tVoiii this locality. They lie iu the rliyo- 

 lit(^ matrix and are similar in typo to tlie 

 Mexican ciystals. The observed forms are 

 III, /, />, o, r/, 1/, /', 

 II J and c. Cross' 

 cites in addition 

 the prism // 51.'>0(. 



Ill, Tul'A ■. I lasl Al, KIIDM I'lKh;; 

 I'l'-.AK. ( 'nl.DltADii. 



m 



m 



I 



17 1 a niMlil 



Flii. L'd.— Tol'A/, CUVSIAL KHOM 

 ri'All. 



The forms observed in 



THOMAS RANGE, UTAH. 



This locality is well represente<l by a lar.ue 

 number of crystals from 1 to 5 mm. in width, 

 some of them doubly terminated. A few have 

 the orifjimil rich wine (!olor, but most aie color- 

 less. Tliey are very similar to tlu^ Mexican 

 crystals in general habit. 



In addition to the forms cited by Allinj;- 

 there occur several (juite 

 rare ones, and on a few the 

 extremely I'are macropina- 

 coid (I jlO()( is well devel 

 oped l)oth front and rear. 



addition to those previously giveu are a |10(){, .1/ 

 )230|, (J )13()j, X J 023 1, X 1 243', // |203|, aud p 

 )401<. Of these .»■ and h occur on but one crys- 

 tal, and are extremely narrow. The i)rism // is not 

 infrequent, while on the other hand the prism \i 

 ; 1 lOf, ligiired by (!. Staidey Brown, ^ does not 

 occur on any (►f the crystals. Many of the crystals 

 show oscillations in their growth, causing reen- 

 trant angles or striated planes instead of sharp 

 edges of intei-section between planes. The edges 

 '".'/, '>.'/, and /// thus appear as if replaced by jdanes, but measurements 

 show them to have no constant angles with the adjacent faces. 



Fig. 20 shows a general combination. It has, besides the common 

 forms, the rarer ones r, />, and //. (No. 45101, U.S.N. M.) 



The most general combination of all is seen in iig. 21, having as 

 narrow forms a, 71/, //, c, />, x, and X. 



l\. TdI' \/ I UVSI Al. 



KUdiM Utah. 



' Am. .h.ur. S(;i., S,l bit., XXXI, p. 432. 

 - Am. .lour. Sci., :{(1 aer.. XXXIII, p. 146. 

 •'Dana's System of Mineralofry, p. I});5. 



