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Earth rocks are largely silicates, combinations of silicon, oxygen, and various other trace elements.

What would a planets geography look like if the crust was primarily composed of ceramics like TiB2, WC, and B4C?

Their hardness would lead me to believe it would be more mountainous and less eroded, but the higher density makes me think it'd be flatter and more eroded.

This world is assumed to have liquid water on its surface, an atmosphere, and possibly life. i.e. Basically the same as Earth

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    $\begingroup$ "What if X happened?" questions are generally too broad, and this one doesn't sound like an exception. $\endgroup$
    – L.Dutch
    Mar 2, 2020 at 2:24
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    $\begingroup$ oxygen is the third most common element in the universe, having a planet with little oxygen in any form is basically impossible. oxygen is even common in asteroids. $\endgroup$
    – John
    Mar 2, 2020 at 2:34
  • $\begingroup$ I note you are capitalizing element names. The words oxygen, boron, etc, are not proper nouns in English. No capital letters. Just FYI. $\endgroup$
    – SRM
    Mar 2, 2020 at 13:16
  • $\begingroup$ Can you break this into several smaller questions? $\endgroup$
    – Zxyrra
    Mar 2, 2020 at 16:47

1 Answer 1

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Let's start with your assumptions.

Have formed very violently, to generate very high temperatures over an extended stretch of the planet's formation

This is what planets do. They form violently. Much of a planet's heat comes from gravitational potential energy when they accrete, and from the kinetic energy of impacts during this time. Earth, for example, is still pretty hot, even after 4.5 billion years.

Be rich in radioactive isotopes to keep the core hot

Long-lived radioactive isotopes which keep stuff hot are, at least on Earth, potassium uranium and thorium. All of these elements do not go into the core. The core is hot not because of radioactive decay, but because it got really hot 4.5 billion years ago, and it has a "lid" in the form of the mantle that stops it from cooling down.

Have an extremely dense core/mantle

Cores are, almost by definition, extremely dense. This is why they are cores. Otherwise, they wouldn't be in the centre of the planet. A mantle would thus be less dense than the core. Otherwise it wouldn't be a mantle.

Be very poor in Silicon, Aluminum, Calcium, Magnesium, and Oxygen

Given that these are some of the most common elements in the universe, you will need to think of a very convoluted process of how did you end up with a planet like this.

Now, to your questions:

How different would this world be from our own?

Very different. Much more different than the spectrum of variability we see in our solar system.

Would/How would life develope here?

There would probably be no life. Life, as we know it, requires water. If there's no oxygen in your planet, then it's too reduced to have water. Oxygen is also required for breathing (i.e., generation of energy). Whether it is as molecular oxygen in the atmosphere or as part of a solid redox exchange reaction (e.g., sulfide and sulfate).

How would volcanism/geography be different?

Probably yes, but we don't know how. No one ever bothered to study the phase equilibria of these compounds in geologically relevant conditions. (I know this because this is what I do for my job)

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  • $\begingroup$ Last month a species of jellifish was found that requires no oxigen. So, at fas as we know, it IS possible. Source: bbc.com/earth/story/… $\endgroup$ Mar 2, 2020 at 13:14
  • $\begingroup$ I've heard of a theory that you could have a planet form near enough to a highly energetic star that all the oxygen and elements of similar or lesser weight were blasted away over time - leaving something like the metallic core of a gas giant, without the gas giant around it. But of course that sounds very inimical to life for many reasons. $\endgroup$
    – Cadence
    Mar 5, 2020 at 3:00

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