104e0784.txt

1 04E-3280784. txt

Isis Veldeman kaartblad 1 04E (32/8) Jl
Belgisch Geologische Dienst BGD-n°104E 784 \ IVd

Date: 06/10/2010
place: Oude groeve Rommersom
x= 188606
y= 162890

In the Rommersom quarry in Hoegaarden sorne iSolated blacks of
quartzite occur and in this case above a dark, lignite rich
clay-layer. Other removed blocksfound in the quarry have on
one side small, cylindrical ho les (probably fossil root ho les)
and a superji.cial coloring by iron-oxides, while the opposite
side is lobed. Afew vertical cracks occur, also with a glossy,
shiny surface, due to an enrichment of hydrated silica (opale)
accorèling to Ledoux (1911). More recent analysis by De Geyter &
Nijs (1983) of this layer excludes opaline quartz on the basis
of X-ray düfraction. What kind of quartz variety it is then,
is still unknown.

The general macroscopic characteristics of the Tienen quartzite
or siliceous quartz arenite is the light gray color, the sugary
aspect ofthefracture sur:face with breakage through the individual
grains instead of fracturing along the grain boundaries ànd holding
fossilized root traces. The beds themselves have an undulating
sur:face and can contain vertical cracks.
For a microscopie description is referred to De Geyter &
Nijs (1983}, Excursion NFWO contactgroep (1983) and Dreesen
et al.(2003).