Assertion: chalcedony | /r/HasAspect | a hardness of 6 to 7
Facets:
Source sentences:
text: The reason for this is that chalcedony has a hardness of 6 to 7 and is highly resistant to both chemical and physical weathering, whereas the host matrix volcanic rock consists of a high percentage of minerals that are both softer and more-readily broken down through weathering and erosion.