346 TJie A?nerican Geologist. December. 1900 
Products of weathering and metamorphism are similar to 
those of the beerbachyte. 
No distinct Hne of demarcation could be drawn between 
these two rock-types. Beerbachyte grades into malchyte 
through an increase in green hornblende with a proportional 
decrease of the pyroxenes in the sam.e manner that horn- 
blende-gabbro merges into gabbro-dioryte. The parallelism 
in the mineral composition of the dike rocks with their deep- 
seated prototypes is further emphasized by the fact 
that some specimens of malchyte {22, 23) contains quartz, 
andesine and biotite, as is the case in the more acid varieties 
of gabbro-dioryte (see p. 338). These specimens may be 
referable to the luciite of Chelius,* although no analysis has 
been made of them. 
The chemical relation of these basic dikes with the gabbro- 
itic facies of the noritic magma is brought out by the following 
analyses. 
The average chemical composition of beerbachyte is given 
under I and that of malchyte under ILt For comparison the 
analysis of hornblende-gabbro (III) and gabbro-dioryte (IV) 
have been reproduced, and the average composition of III-IV 
and I-II given under V and \T respectively. 
I II III IV V VI 
Si02 46.29 45.66 44.79 47-20 45.99 45.97 
TiO.. 1. 21 1.39 184 84 1.34 1.30 
AhOa 17.16 16.26 15.18 18.64 16.91 16.71 
Fe.Oa 2.57 2.97 4.13 1.96 304 2.77 
FeO 9.87 8.51 8.21 6.82 7.51 9-17 
MgO 7.79 10.21 7.93 8.28 8.13 900 
CaO 12.04 12.25 14.10 11.52 12.81 12.14 
Na.O 2.21 1.34 2.18 2.91 2.54 1.77 
K..,0 16 .31 .30 .28 .29 .13 
Ign 51 -92 1-33 1-44 i-38 -74 
Total 99-8i 99.82 99.99 9989 99-94 99-8i 
Spec.gr 3.06 3.04 3.04 3.02 3.05 3.03 
It will be noticed at a glance at the above tables that, ex- 
cepting slight differences in the proportions of FeO and MgO, 
* Notizbl. des Ver f. Erdkh., 1894, IV Folge, p. 2a. 
tThe material for these analyses was obtained by uniting an equal 
amount (by volume) of rock powder from six specimens of beer- 
bachyte ( 3, 5, 6. 10. 14, 16) and five of malchyte (4. 7, 22,, 20, 21)). 
