# Guesstimate the weight of this rock

**URL:** <https://boards.straightdope.com/t/guesstimate-the-weight-of-this-rock/405978>\
**Category:** Factual Questions\
**Created:** [May 29, 2007, 7:57pm UTC](https://boards.straightdope.com/t/guesstimate-the-weight-of-this-rock/405978 "2007-05-29T19:57:25Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [May 30, 2007, 5:30am UTC](https://boards.straightdope.com/t/guesstimate-the-weight-of-this-rock/405978/21 "2007-05-30T05:30:33Z")

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> [@](#):
>
> OTOH good luck finding common rocks at Earth’s surface with 5X the density of water. Most solid silicates (say, granite) have SG’s of 2.6 to 2.8. Basalt trends higher, but often is vesicular.

I think I was basing that assumption on the average density of the Earth, which is dominated by the density of iron. Crustal rock would indeed be lighter.

Note to self: Edit “typical rock density” factoid in brain.

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