Classification - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 75

characterized by the predominance of augite instead of olivine. The felsic constit-
uents are nepheline in K 2 O-rich ankaratrite proper, nepheline + leucite in leucite
ankaratrite and leucite in melaleucitite. A venanzite is constituted of olivine, melilite
with some leucite and kalsilite. Diopside and phlogopite appearing as late crys-
tallization products are also present. Coppaelite is a melilitite with kalsilte. Cop-
paelite has been described from Coppaeli di Satto (now Coppaello), Central Italy.
Coppaelite and venanzite lava flows have been found to erupt in the eastern part of

Roman co-magmatic province.
Washington (1927) coined the term italite to represent a mono-mineralic effusive
rock type containing essentially entirely of leucite with minor amounts of augite,
glass, and other phases. The type locality of italite is Villa Senni, where the rock
comprises >90 % leucite, the remainder is constituted of melilite, clinopyroxene,
mica, Fe-Ti Ti oxides and apatite. The term leucitite (called albanite in old literature),

refers to a rock containing leucite and augite in nearly equal proportion with a small
amount of other phases. The type localities for leucitites are Lake Cargelligo,
Begargo Hills, Flagstaff Hills, Bygalorie and Condoblin (all localities from New
South Wales, Australia). In various localities of New South Wales, modal volume
percentage of leucite (18

-

- 36 %), clinopyroxene (33 - 45 %), olivine (3 - 20 %) and

Fe 20 %) is variable. The other salic phases in these leucitites include

nepheline, alkali feldspar and apatite; and the hydrous phases are constituted of
phlogopite and amphibole. Leucitites have also been reported from Gaussberg,
Antarctica by Sheraton and Cundari (1980). They are also reported from Mt. Jugo
and Colli Albani volcanic

- Ti oxides (8 -

fields.
Leucitites are associated with tephrites, basanites, phonolites, and nepheline-
bearing rocks in many localities of Uganda and Italy. When olivine is present in
addition to leucite and clinopyroxene, the rock is called olivine leucitite. In earlier
literature, the term leucite basalt had been used to designate olivine leucitites.Asa
basalt always contains plagioclase in addition to clinopyroxene, the term “ leucite

basalt should be avoided. Holmes and Harwood (1937) preferred to use the term

ugandite when there was a signi

”

cant amount of olivine. If the proportion of leucite
is greater in an olivine leucitite, it is called mikenite (Finckh 1912). Ferguson and
Cundari (1975) preferred to call ugandite to those rocks with a colour index in the
range of 60

75 vol%.
A melilite, clinopyroxene and leucite-bearing rock is called melilite leucitite
(earlier called cecilite or vesbite, depending on different proportion of these three
phases). In Villa Senni some vesbites contain 50

-

60 % leucite, 18 23 % melilite

- -

and 16 20 % (all in vol%) clinopyroxene with such accessory minerals as titano-

magnetite, apatite, calcite, etc. Some of the melilite leucitite from Capo di Bove is
constituted of 42 % leucite, 23 % melilite and 16 % clinopyroxene and remainder is
constituted of accessory phases.
The term katungite (named after the extinct Katunga volcano, of which it is the
sole product) has been used by Holmes (1950) for a rock consisting of olivine,
melilite and leucite with minor amounts of apatite, phillipsite, natrolite,

-

fluorite, and

rare nepheline. The rock contains 16 25 % leucite, 40 50 % melilite and 22 25 %

- - -

olivine (all in vol%). The accessory phases include ha ü yne, zeolite, apatite, and