For example, boracite forms pseudo-cubic crystals which become truly cubic at 265°, with a distinct change in density; leucite behaves similarly at about 560°.
Klaproth had discovered the presence of potassium in leucite and lepidolite, it occurred to L.
Finding vegetable alkali in certain minerals, such as leucite, proposed to distinguish it as potash, and at the same time assigned to the mineral alkali the name natron, which survives in the symbol, Na, now used for sodium.
News, 1864, 10, p. 181), and, associated with rubidium, at Diirkheim; it is also found in lepidolite, leucite, petalite, triphylline and in the carnallite from Stassfurt.
Leucite and nepheline lavas are here abundant.
In the Siebengebirge the little crater of Roderberg, with its lavas and scoriae of leucite-basalt, is posterior to some of the Pleistocene river deposits.
In the region between the Northern and Southern Rockies, the plains are interrupted by minor Mountain groups, volcanic buttes and lava flows, among which the Leucite Hills and Pilot Butte are prominent examples.
A syenite massif of this age occurs at Mittagong; and leucite has been discovered in Carboniferous basalts by David.
The Cainozoic series of New South Wales contains many interesting volcanic rocks, including leucite-basalts, nepheline-basalts and sodalite-basalts.