1248 
The metamorphoses described above, which are connected by all 
sorts of transitions show great resemblance to those found in blocks 
of leucite-tephrite of the Fosso di Caucherone (Vesuvius) *) which 
have been altered by the action of fumaroles. The microlithes and 
phenocrysts of augite have become yellow, and the extinction-angles 
agree with those of an aegirine-augite, sometimes with those of 
aegirine. Haematite is abundant with the exclusion of magnetite. 
The biotite and amphibole show modifications of colour. 
In the “sperone” of Latium, likewise a metamorphic rock which. 
by transitions is connected with a normal black leucitite, the normal 
green augite has been altered into a gold-coloured one, whose angle 
c:c varies between 65° and 85° whilst likewise the original magnetite 
has more or less completely disappeared. Moreover there is often 
formed a yellow melanite’). 
Finally a green-yellow aegirine-augite occurs in varieties of the 
shonkinite of the Katzenbuckel (Odenwald) which has been modified 
by pneumatolytic processes*). The tron-ore has here been altered 
into pseudobrookite, the feldspars are more or less zeolitised. Analyses 
made by LATTERMANN indicate that in the rock modified by pneuma- 
tolysis, the percentage of Fe,OQ, had increased from 5,86°/, to 8,51°/,, 
whilst in the variety with yellow augite the FeO of 3,23°/, which 
had been found in the original rock, had entirely disappeared. Like- 
wise in the analyses of sperone the Fe,O,‘) dominates strongly over 
the FeO; evidently the metamorphosing agencies had an oxydizing 
influence. The modification of the optical properties of the gold- 
coloured pyroxene tends to prove that the Na,O percentage has 
also been increased, which could not be concluded from the different 
analyses. 
In connection with what has been said a second locality of rocks 
with gold-coloured pyroxene may be mentioned (II of the annexed 
map) situated directly South of the road from Panarukan to Besuki 
at mile-post 18. At the northern foot of a bare hill a porous light-grey 
rock that microscopically proves to be rich in gold-coloured pyroxene, 
appears between rocks of dark-grey biotite-leucite-tephrite. 
1) A. Lacrorx. Etude minéralogique des produits silicatés de l’éruption du Vésuve 
(avril 1906). Nouv. Archives du Muséum. 4e Série. Tome IX, 1907, pp. 73, 94. 
2) A. Lacrorx, |. c. p. 95. 
3) W. FREUDENBERG. Geologie und Petrographie des Katzenbuckels. Mitt. Groszh. 
Badische Geol. Landesanstalt V. L. Teil, 1906, p. 81. 
4) V. Sapatini. I Vulcani dell’ Italia centrale. I. Vulcano laziale. Mem. Carta geol, 
d'Italia, X, 1900, pp. 150, 163. 
