Answer:
a. red-brown
Explanation:
Specular Hematite is a mineral which is found in rocks and soils. The crystal of specular hematite is greyish black in color but it can form the streak of reddish color which is due to the presence of iron oxide. It has metallic luster which gives a look like silver and has shiny flakes.
"The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya.<span> <span>Wikipedia."
https://www.google.com/search?q=He+Silurian+period+occurred&rlz=1C1RUCY_enUS760US760&oq=He+Silurian+...
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