Monte Madarosa Quarry, Roccolo Pass, Chiampo, Vicenza Province, Veneto, Italyi

Regional Level Types
Monte Madarosa Quarry	Quarry
Roccolo Pass	Pass
Chiampo	Commune
Vicenza Province	Province
Veneto	Region
Italy	Country

Abandoned basalt quarry located at 350 mt from the Roccolo Pass.
Remnants of columnar basalt are still observable.

The basaltic rock is rich in mantle peridotite xenoliths (spinel lherzolite), which show reactions at the contact with the host basalt and small basaltic veinlets that have partly invaded the xenoliths. The inner portions, i.e. far from the xenolith-host basalt contact, show coarse-grained texture. Olivines (forsterite) generally show undulose extinction and orthopyroxenes display exsolution lamellae. The latter commonly show reaction rims against olivine and clinopyroxene. These rims consist of fine-grained olivines and clinopyroxenes set in a glassy matrix. More importantly, these rims and the host basalts are not in contact. Spinel occurs as holly-leaf shaped grains, whereas spinels in contact with the host basalt show opaque, Cr-enriched rims. The reaction zones along the contact between xenoliths and the host basalt consist of fine olivine and clinopyroxene(±glass) aggregates, which replace former pyroxenes. In the reaction zones, large olivines with embayed grains also occur.
Vitreous anorthoclase inclusions in basalt are quite rare.

Natrolite is the typical in the small basalt cavities. In the associated tuff, in addition to pyrite, it is possible to find offretite, which appears both as spherulitic crystal aggregates and as submillimetric individual crystals. Furthermore, offretite (with "phillipsite", "heulandite", analcime, baryte, aragonite, and allophane) is also present in the oucrop along the dirt road Passo Roccolo - Monte Calvarina, ca. 300 m southeast of the pass, in the municipal territory of San Giovanni Ilarione (Verona province) [see https://www.mindat.org/loc-312008.html].

Other Regions, Features and Areas containing this locality

References