Ferruginous Quartz is a quartz that has yellow, red, or brown tones from inclusions of iron compounds, usually iron oxides and hydrous iron oxides (i.e. hematite or limonite). It's proper geological name is Ferruginous Quartz.

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Common misnomer: Hematoid Quartz.

- oid: a suffix meaning “resembling,” “like,” used in the formation of adjectives and nouns (and often implying an incomplete or imperfect resemblance to what is indicated by the preceding element), such as: alkaloid; anthropoid; cardioid; cuboid; lithoid; ovoid; planetoid. Therefore, if this crystal were hematoid it would look like Hematite.