Locations with anomalous finds of Unusually Pure Silica
Example; “Ocean Silica”Example; “Herkimer Diamond”
Example; “Libyan Dessert Glass” (LDG)
Example; “McMurdo Dry Valleys”
Astronomers continue to research the composition of cometary bodies. The results from the recent Star Dust and Deep impact missions are being evaluated by many.
A recent paper by Britt, etal "SMALL BODY DENSITY AND POROSITY: NEW DATA, NEW INSIGHTS"
To first order comets are mixtures of water ice with a dust composed of hydrated silicates, mafic silicates, and organics. While there are a number of other vola-tile species, water ice dominates the mass balance of the volatiles. Water ice has a grain density of 0.93 g/cm3. Cometary dust compositions are not well known yet, but a reasonable analogue may be CI car-bonaceous chondrites which are composed of the same sort of silicate and organic mixture thought to domi-nate the cometary dust.
A significant fraction of the carbonaceous chondrite
meteorites are hydrated silicate [1], that
is silica in a hydrated bonding with water. The photograph
below shows the Tagish Lake meteorite, which has been
identified as having matrix dominated by hydrated silicate
minerals
The Tagish Lake meteorite (NASA JSC).
The Perigee: Zero hypothesis suggest that a significant
amount of water and silica (as sand and clays) was accreted
unto the earth during the impact events of the last 15,000
years.
[1] CATASTROPHIC DISRUPTION OF HYDRATED TARGETS: Implications for the Hydrated Asteroids and for the Production of Interplanetary Dust Particles
G. J. Flynn, Dept. of Physics, SUNY-Plattsburgh and D. D. Durda Southwest Research Institute, Boulder, CO