Magnetite is a type of iron oxide that is naturally occurring, and it is what makes black sand magnetic. ... Because of its color, this sand gets much hotter than regular sand. Are magnets natural or manmade? Magnets can be natural and manmade. Natural magnets are found in the earth ...
CantheanomalousX-raypulsarsbepoweredbyaccretion 系统标签: accretionpulsarsrayanomalousaxpspowered a r X i v : a s t r o - p h / 9 9 0 3 1 9 0 v 1 1 2 M a r 1 9 9 9 CantheanomalousX-raypulsarsbepoweredbyaccretion? X.-D.Li 1 ABSTRACT Thenatureofthe5−12s“anomalous”X-...