Gabbro

Listed in our range under Granite.

Star Gate

Star Gate is an exceptional Precambrian gabbro from Zimbabwe — a plutonic igneous rock with a deep black groundmass and characteristic silvery white plagioclase mineral dots, distributed like sparkling stars across a dark night-sky character. Internationally also traded as New Galaxy, African Silver, Silver Galaxy and African Star; used for statement wall claddings, bar counters, designer kitchen worktops, memorials and monuments and prestige interior surfaces with a dramatically dark starry-sky material effect.

Petrographically, Star Gate is a gabbro (DNSA stone 5623) — a basic plutonic igneous rock of the gabbro family. In international trade the stone is traditionally listed as “granite”, because in fabrication and mechanical properties it is handled like a classical hard stone. At ROSSITTIS we classify Star Gate in the granite family in line with trade usage, following the widely established trade convention for Zimbabwean gabbros from the Great Dyke. Important: “Negro Stargate” (South Africa) and “Stargate Cosmos” (Brazil) are completely different materials — when ordering, specify the Zimbabwean origin.

Gabbro Zimbabwe

Available as: Slabs, Skirting, Tiles and flooring slabs

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About Star Gate

Star Gate shows an exceptionally characterful gabbro with a dramatic starry-sky look. The groundmass is a deep black norite/gabbro matrix with a coarse-grained isotropic structure. Characteristic are the silvery white plagioclase mineral dots typical of Star Gate — these pale crystals are distributed in varying sizes across the black groundmass and create an unmistakable starry-sky effect. The designation 'Star Gate' and the synonyms 'Galaxy', 'Silver Galaxy' and 'New Galaxy' describe this material effect aptly — much like the famous Indian Star Galaxy, but with silvery rather than golden shimmering dots. The individual plagioclase crystals reflect the light with subtle silvery blue schiller reflections that shift with the incidence of light. On a polished surface the stone develops a dramatically dark depth with a sparkling starry character — the stone looks like a captured piece of night sky.

Geologically, Star Gate is a Precambrian gabbro from Zimbabwe — a basic plutonic igneous rock originating from the Great Dyke of Zimbabwe (related to the better-known Nero Assoluto Zimbabwe from Mutoko). Petrographically a gabbroic plutonic rock dominated by plagioclase feldspar (labradorite-bytownite) and dark pyroxene minerals (augite/hypersthene) — the latter two are responsible for the intense black colouring and the high bulk density. The DNSA dimension stone reference lists the material under entry 5623 with the main name STAR GATE and several trade synonyms. Several synonyms are in circulation in international trade: New Galaxy (the English trade name — referring to its Star Galaxy-like character), African Silver, Silver Galaxy, African Star and Star Gate Black. The trade name 'New Galaxy' refers to the visual kinship with the famous Indian Star Galaxy from Andhra Pradesh, but with silvery plagioclase dots instead of golden bronze mica dots. IMPORTANT: there is an unrelated 'Negro Stargate' (South Africa, Rustenburg) and 'Stargate Cosmos' (Brazil) — both are completely different materials. When ordering we recommend always specifying the origin (Zimbabwe).

Technically Star Gate shows exceptionally strong values for a gabbro: bulk density 3,068 kg/m³ (exceptionally high — about 14 % heavier than a typical granite, typical of the gabbro/norite family), water absorption of only 0.11 % (extremely low), Mohs hardness 6–7. Full frost and acid resistance is confirmed for it as a silicate rock — wine, lemon juice, vinegar or sanitary cleaners leave no etch marks as they would on marble or limestone. The values are typically comparable with other Zimbabwe gabbros such as Nero Assoluto Zimbabwe (compressive strength ~228 MPa, flexural strength ~31 MPa). This makes Star Gate fully everyday-capable for the most demanding interior and exterior applications.

At ROSSITTIS we stock Star Gate as a raw slab in 10, 20, 30 and 40 mm thickness (standard gauges plus solid applications for stairs or bar counters), in tiles for floor and wall applications, as a skirting and for project-specific cutting to size. The available standard finish is polished (a classic dark gloss with the full starry-sky schiller effect — the typical treatment for this material).

Compared with other black gabbro and granite grades with shimmering dots, Star Gate is a special choice: Star Galaxy (an Indian granite from Prakasam, Andhra Pradesh) is the more famous golden version with characteristic golden bronze mica dots — the more exclusive Indian grade; Nero Assoluto Zimbabwe (Mutoko, Zimbabwe) is more uniformly black without pronounced star dots; Black Galaxy India is similar to Star Galaxy with bronze dots. Within the black building stones with a starry-sky look, Star Gate positions itself as the African version with silvery rather than golden shimmering accents — an economically attractive alternative to the more exclusive Star Galaxy. For architectural projects with a dramatically dark starry-sky material effect — designer bar counters in premium restaurants, statement kitchen islands, prestige wall claddings with a memorial character, monuments and building applications with a fine shimmering accent — Star Gate is an expressive and economically attractive choice within the African black hard stone range.

In stock

Current availability from our warehouse.

50 slabs in stock · plus 14 blocks

Thicknesses: 1–4 cm · Finishes: Polished · Available as: Slabs, Skirting, Tiles and flooring slabs

Updated daily from our live stock.

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Technical data

Guide values for the stone type, taken from manufacturer and test reports. Natural stone is a natural product — individual batches and slabs can differ. For critical applications, request slab-specific test data.

Druckfestigkeit 226,2 MPa

Biegezugfestigkeit 22,8 MPa

Wasseraufnahme 0,11 %

Suitability by application

Finishes

Star Gate is available in a range of finishes. The finish affects appearance, feel and the care it needs.

Polished

Polishing is the most classic finish in the hard stone segment — a mirror-smooth, high-gloss surface with the highest possible colour intensity and maximum depth effect in the mineral structure. As an acid-resistant silicate stone, polished granite is easy to care for and the first choice for kitchen worktops, wall claddings and prestigious exposed surfaces.

Care & fabrication

As a Zimbabwean gabbro, Star Gate is an exceptionally robust hard stone with extremely low water absorption (0.11 %), full frost and acid resistance and very high compressive and flexural strength. Wine, lemon juice, vinegar, cola, sanitary cleaners or descalers leave no etch marks as they would on marble or limestone — the stone is considerably easier to look after and ideally suited to intensive everyday use.

For polished black surfaces one particular point applies: the mirror-like depth shows every water and wipe-streak detail all too clearly, because pure black offers no masking effect. Drying off with a polishing microfibre cloth after damp cleaning is mandatory for a clear appearance and a fully sparkling starry-sky effect.

For interior applications we recommend a light silane- or polysiloxane-based impregnation at first installation. On polished surfaces a refresh every 8–10 years is enough; on heavily used kitchen worktops, check every 5 years. The impregnation protects against grease rings on highly polished surfaces.

Day-to-day care is done with a pH-neutral natural stone cleaner and a soft cloth or microfibre mop. Clear warm water is usually enough. Acidic cleaners are in principle unproblematic (the stone is acid-resistant), but should nevertheless not be used, because they can attack the impregnation.

For kitchen worktops Star Gate is outstandingly suited: exceptionally cut- and scratch-resistant, insensitive to heat, acid-resistant and with excellent stain repellency thanks to its extremely low water absorption. The dramatic starry-sky look gives designer kitchens an extraordinary visual character. Hot pots and pans can be set down directly for short periods, but longer heat exposure above 250 °C should still be avoided.

For exterior applications Star Gate, with its confirmed frost resistance, exceptional strength and low water absorption, is stable in the long term under weathering. The surface finishes available from stock are listed in the »Finishes« block further down.

For pool surrounds, outdoor terraces and fountain enclosures, a slip-inhibiting textured finish is mandatory — on polished exterior surfaces there is a high risk of slipping when wet. In hot climate zones the dark ground tone stores a great deal of solar energy — on exterior surfaces used barefoot, such as pool surrounds, this can lead to uncomfortable surface temperatures in Mediterranean or subtropical climates.

Frequently asked questions

What is Star Gate geologically?

Star Gate is a Precambrian gabbro from Zimbabwe — a basic plutonic igneous rock dominated by plagioclase feldspar (labradorite-bytownite) and dark pyroxene minerals. Related to the famous Nero Assoluto Zimbabwe from the Mutoko quarry area (the same Great Dyke of Zimbabwe complex). Petrographically a gabbroic plutonic rock with a coarse-grained isotropic structure. DNSA lists the material under entry 5623.

Which synonyms are there?

In international trade, Star Gate also runs under the designations New Galaxy (the English trade name — referring to its Star Galaxy-like character), African Silver, Silver Galaxy, African Star and Star Gate Black. IMPORTANT: there are unrelated stones of the same name — 'Negro Stargate' (South Africa, Rustenburg) and 'Stargate Cosmos' (Brazil) are completely different materials. When ordering we recommend always specifying the origin (Zimbabwe).

What is the characteristic starry-sky effect?

Star Gate shows an unmistakable starry-sky effect from silvery white plagioclase mineral dots distributed in varying sizes across the deep black groundmass. The individual plagioclase crystals reflect the light with subtle silvery blue schiller reflections that shift with the incidence of light — hence the trade designation 'Star Gate' and the synonyms 'Galaxy', 'Silver Galaxy', 'New Galaxy'. The material effect recalls a star-covered night sky.

Which technical values does Star Gate have?

Exceptionally strong values: bulk density 3,068 kg/m³ (exceptionally high — about 14 % heavier than a typical granite, typical of the gabbro/norite family), water absorption of only 0.11 % (extremely low), Mohs hardness 6–7. Full frost and acid resistance is confirmed for it as a silicate rock. The values are typically comparable with other Zimbabwe gabbros such as Nero Assoluto Zimbabwe (compressive strength ~228 MPa).

Star Gate or Star Galaxy?

Both are dark hard stones with a characteristic starry-sky look, but they differ in origin and in the colour of their shimmer. Star Galaxy (an Indian granite from Prakasam, Andhra Pradesh) is the more famous and more exclusive grade with characteristic golden bronze mica dots — the warm Indian version. Star Gate (a Zimbabwean gabbro) is the more economically attractive alternative with silvery plagioclase dots — the cooler African version. Both are suited to statement settings; the choice is an aesthetic decision between warm golden (Star Galaxy) and cooler silvery (Star Gate) accents.

Is Star Gate suitable for a kitchen worktop?

Outstandingly suited — it is regarded as one of the best stones for kitchen worktops. With Mohs hardness 6–7, extremely low water absorption (0.11 %) and full acid resistance, the stone is cut-, scratch- and heat-resistant and does not absorb the acids in wine, lemon or vinegar. The dramatic starry-sky look gives designer kitchens an extraordinary visual character.

Which surface finishes are available for Star Gate?

The surface finishes available from stock are listed in the »Finishes« block on this page.

Is Star Gate suitable for memorials and headstones?

Outstandingly suited — Star Gate has been used for memorials and monuments for years, much like the related Nero Assoluto Zimbabwe. Its long-term stability under weathering, low water absorption, frost resistance and dramatic starry-sky look make the stone a fitting choice for dignified memorial applications. Compared with Nero Assoluto Zimbabwe, Star Gate is more attractive in price, with the additional characteristic of its starry-sky shimmer.

What does Star Gate cost?

The price depends on the batch, thickness, surface finish and fabrication — with natural stone there is no serious flat rate per square metre. Business customers see prices once their B2B account is activated; private customers receive a complete quote through a fabricator near them.