Ferruginous quartz cluster Siderite well-formed crystals displaying parallel growth

well-formed crystals displaying parallel growth and twinning

cementing it all together with sedimentary debris

I'm not hip enough on my crystallography to tell you what types of twinning we are looking at

but do not lick it or put it in your mouth

This calcite specimen from Santa Eulalia has a layer of calcite druzy with several larger modified rhombohedral calcite crystals perched atop

Ferruginous quartz cluster Siderite well-formed crystals displaying parallel growthLocale: Morocco Approx dimensions: 4. 5 x 3 x 3", longest crystal 5. 5 cm Approx weight: 627g Known as red or ferruginous (iron bearing) quartz, this unusual variety of quartz gets its color from iron oxides, typically hematite. The quartz in this specimen initially grew colorless; broken crystals along the edge reveal the quartz crystals have a clear core bordered by a thin top layer of brick red quartz. A change occurred during the growth process