Aggregate for Road Base & Concreting
Gneate is a superior high density basalt media, suitable for use as a concrete aggregate, road base and Rail Ballast.
QUARRY REGISTRATION CERTIFICATE (No.2017-123)
Rock/Material Types: Olivine Basalt
Rock Material Group: Basic Igneous
Nominated Products:
Unbound Paving Material (Type 2 & 3)
Cover Aggregate (A,B,C & D)
Concrete Aggregat (Coarse & Fine)
SUITABLE USE
The basalt is predicted to be durable.
Olivine basalt equivalent to the supplied sample is predicted to be suitable as a source
for the production of aggregate for use in roadbase.
Basalt of the type represented by the supplied sample is predicted to be suitable for use
as a source of rail ballast and rip rap.
PRIMARY COMPONENTS
• 45% feldspar (plagioclase possibly with minor K-feldspar)
• 17% clinopyroxene
• 6% olivine
• 8% opaque oxide (magnetite and/or ilmenite)
• 19% black basaltic glass (with mainly opaque oxide microlites)
• 2% late yellow glass (siliceous glass)
• <1% apatite
Secondary minerals
• 2% yellow to green clay of smectite style (nontronite)
• 1% calcite
• <1% hematite
COMMENTS & INTERPRETATIONS
The supplied rock sample (basalt sample 001), is considered
to be partly glassy basalt, a basic volcanic rock probably from the edge of a thick lava
flow.
For engineering purposes, the rock represented in the supplied sample may be
summarised as:
• olivine basalt (a basic volcanic igneous rock type)
• finely crystalline and partly glassy
• sub-ophitic texture
• non-porous
• surficially weathered
• moderately altered
• secondary mineral content is about 3%, comprising brown smectite clay, calcite
and <1% hematite)
• carrying about 2% late glass which is regarded as a less durable component
• hard
• strong
MICROSCOPICALLY
Microscopically, all fragments are seen to display finely porphyritic, hypidiomorphic, finely crystalline and partly glassy igneous textures of basic volcanic style.
Primary mineral grains are mainly 0.1 to 0.6 mm in size and there is an interstitial,
interconnected, black, glassy mesostasis with a black glass component.
Irregularly shaped
interstitial spaces are generally filled by a late, fractionated yellow to orange
glass and minor calcite.